How wide should the tires be on your road wheels? Here are my recommendations for the best bike tire and wheel sizes to improve speed, comfort, and handling.

One of the biggest shifts in road cycling in recent years has been the move to wider tires.  By spending less than $100/£70/€90 on a pair of 25mm or 28mm wide tires, many cyclists have been led to believe their comfort, speed and handling will immediately improve over what they experience on the 23mm wide tires that most of us have used for years.

Unfortunately, merely shifting to wider tires is simplistic, incomplete or, depending on your set-up, a partially or completely wrong way to improve your ride performance.  It’s not surprising that all of us busy and budget-conscious road cycling enthusiasts would be attracted to a quick and cheap solution to better riding.  But unfortunately, it’s not that easy (or quick or cheap).

In this post, I’ll try to give you a complete explanation of how wider tires and/or wider wheels can give you some or all of the better comfort, speed and/or handling you are looking for or make no difference or make things worse.


Related: Road Bike Wheels – How To Choose The Best For You



I’ll also try to do a few things that I haven’t seen in a lot of other articles that have addressed this topic.  First, using published tests and analysis where available, I’ll quantify the benefits and drawbacks that previously have only been claimed.  For example, exactly how much is rolling resistance reduced using wider tires and how much will it reduce your time over different distances?

Second, I’ll look at what the interrelated effects are of using a wider tire or wheel rather than looking at them in isolation as most do.  For example, what effect does a wider tire on a stock size wheel have on your handling?  Or, with the wheelset you bought to improve your speed, how wide a tire should you go with?

Finally, I’ll make all of this relevant to you, my fellow road cycling enthusiasts rather than to cyclists in general or to triathletes, commuters, recreational, or gravel riders who ride different speeds, distances, road surfaces, and courses.

At the end of all of this, I’ll lay out my recommendations for the best combinations of bike tire and wheel sizes for road cycling enthusiasts based on your comfort, speed and/or handling priorities.

In a previous post (currently being updated), I’ve reviewed the best road bike tires which covered standard and wider sized tires used by enthusiasts today.  After completing this post, I’ve written a review of wide alloy wheels that can bring you some of the ‘wider’ performance benefits on a reasonable budget, or at least a smaller one than what you might spend to get the full performance benefits of wide all-around carbon wheels that I previously reviewed here or aero wheels, reviewed here.


Most new road bikes with rim brakes come with wheels that are designated 17C or are 17mm wide between the tire bead hooks that run along the inside of each rim.  These bikes are also generally specified with tires that are 25C or 25mm wide on their outside before inflation.  It may seem odd to call out the inside width of the wheel’s rim and the outside width of an uninflated tire but it will become clearer why later.

rim and tire widths

If you look at the bikes Bike Radar selected for their bike of the year awards back in 2016, you’ll see that 3 out of the 4 rim brake bikes that were picked as the best in their price ranges were sold with 15C stock wheels while 2 came with 23C tires and the other 2 with 25C ones.  If you look at the 11 rim brake bikes that made up their £2,000 to £2,750 or US$2800 to $3800 category where many road cycling enthusiasts shop, 8 of those 11 bikes were equipped with 15C wheels and 8 with 25C tires.

As is the case with most new bikes, none of these wheels or tires were, or today are, high performance or terribly comfortable, no matter their size.  Unfortunately, you don’t usually have the choice to switch stock wheels and tires for another set without an extra charge or for most, take delivery of the bike without any wheels and get the price reduced.

Skip forward to the present day and most stock wheels on new disc brake, enthusiast-level road bikes (which far outsell rim brake ones) use 17C or 19C rims and 25C or 28C tires. If you have a model year 2016 to 2018 bike (rim or disc brake) it’s likely in the narrower of those two options. Since then, the newer the bike, the more likely it is a road disc bike and has 19C rims and 28C tires but many still are sold with 17C rims and 25C tires.

You’ll often see these rim widths referred to as 622x17C or just 17C on the wheel spec sheets and as 700x25C or just 25C on the tire boxes rather than or in addition to the mm sizes they refer to.  The first number is the rim or tire diameter which is the same for nearly all road bike wheels and the second one is the inside rim and outside tire widths, which vary.  The C designation is one set out by a cycling group called ETRTO (for European Tyre and Rim Technical Organization) that has worked with manufacturers to standardize around sizes.

The trend today is toward road cycling wheel rims that are 17C or wider and tires that are 25C or wider.  Starting mid-year 2015 and continuing in the 2016 model year Fulcrum, Campagnolo and Mavic have begun selling some 17mm wide upgrade rim brake wheels. By model year 2017, this transition should be complete.

Most new road bikes that have disc brakes come with 17C stock wheels and 25C tires.  As this “road disc bike” category is only a few years old, bike companies have made their frames wide enough to fit and deliver the benefits of these and even wider wheels and tires.

Whereas 17C stock wheel rims typically have an outside width of 21-23mm wide across their brake tracks, 19C stock wheel rims typically run 25-27mm outside widths.

The drawing below shows these rim width ranges and also the rim profile that often, though not always, accompany these widths.

Comparing Alloy Wheel Rim Widths and Profiles

Years ago ETRTO recommended tire widths that would, in their view, safely fit each internal rim width or size (13C, 15C, 17C, 19C, etc.).  The concern was that a tire too wide for a rim could result in unsafe handling or a failure in the tire sidewall or rim.  On the other hand, a tire too narrow for a rim might disengage from the rim and cause a blowout.  While some companies, shops, and riders still use the chart derived from these recommended combinations as if it were a sacred tablet (or perhaps a lawyer’s commandment), I hesitate to reproduce it here because it is badly out of date.

Why?  The ETRTO chart doesn’t account for the range of tire pressures, tire materials, tire bead designs, rim wall thicknesses, rim hook designs, riding speeds and probably a half dozen other factors including aero performance, rolling resistance, tubeless tires and other use scenarios and product designs that have come about since the standards were developed.

Many of the leading wheelset companies recommend tire widths narrower than the ETRTO ones to maximize aero performance. Most design their rims for 25C tires and don’t recommend you use anything wider than a 28C tire.  These rim/tire width combinations run safely.


With that as background, what changes when you move to rims wider than 15C or 17C and tires wider than 23C or 25C?  It’s really three things – comfort, speed, and handling – to varying degrees and not always in a good way depending on what combination of tire width, rim width and rim profile you choose.

Let’s take them one at a time and then together.


With a wider rim or a wider tire or both, you don’t need to pressure your tires as high as with a narrower one to support your weight.  All things being equal (temperature, outside pressure, humidity, rim and bead design, tire model, just to name a few), you need the same amount of air to hold your weight up in the larger volume of the space created by the wider rim and/or tire as you do with narrower ones.  And we all know that riding at a lower pressure makes the ride more comfortable because the tires deflect more at lower pressures to absorb bumps and uneven road surfaces.  So if you have a wider rim and/or tire, you can ride more comfortably by lowering your tire pressure.

For years, ‘real’ roadies and racers used to blow up 20C and 23C wide tires to 110 to 120psi for what we foolishly thought and felt would make us go faster (less tire surface touching the road, more aero shape), our tailbones and soft tissue be damned.

Now it’s not uncommon for road cyclists to ride tube/tire combinations at 70 to 90psi (and tubeless ones 10-20psi lower), all with wider rims and tires.  If you are doing a century, sportive, gran fondo or just riding irregular pavement on your long training or fun rides, lower pressure tires can make the ride a whole lot more enjoyable.

Why not just lower your pressures on whatever combination of rim and tire width you are running now to get more comfort?  You can do that to a degree (maybe 5-10psi), until the point where the tire loses the shape you need it to handle well and you are more prone to getting a ‘pinch flat’ from squeezing your tube between the rim and tire bead (Type 1) while cornering.  Too low tire pressure can also cause the tube to pinch flat when you hit something straight on (Type 2) and there’s not enough air to prevent the tube from folding on itself.



No matter what width tire you are running, the key here is to find the right pressure to inflate your tire.  For that, I suggest you start with a table provided by your tire company and a little trial and error of your own.  Tire companies vary quite a bit in what they recommend or even how specific they are willing to get as you can see in the examples for Zipp tires and Michelin ones on the left and right, respectively, below.  (Can’t even find one from Continental, maker of my recommended Grand Prix 5000.)

Zipp and Michelin tire pressure recommendations

Zipp and Michelin tire pressure recommendations

I find it helpful to start with the tire company’s typically conservative recommendation and experiment by dropping the pressure in 5psi increments to find the level of comfort and handling performance that feels right for the speed, roads and bike handling I’m doing.

Putting a 25mm tire on many of the 15C wheels that come on new bikes sold before 2016 is kind of like putting lipstick on a pig.  Many of these stock wheels aren’t terribly compliant or comfortable to start with.  Putting an oversized tire on them softens the ride but doesn’t do anything to improve the speed or handling.


The 1) tire’s rolling resistance, 2) wheel’s rim width and profile, and the 3) relationship between the rim and tire width all contribute to how much added speed you can get… or lose going with a wider tire and/or rim.

Let me review each of these individually.

Improved 1) rolling resistance, or the reduction in friction between the tire and the road, is often written about as a primary benefit of wider tires.  Tests by a range of independent sources I charted in my review of the best road bike tires and those done by private testers hired by cycling publications show that, all else being equal, a wider tire will reduce your rolling resistance and therefore speed your ride.

But, the amount of rolling resistance reduction you get going from a 23C to a 25C to a 28C tire is only about a couple of watts combined for the front and back tires regardless of the tire, tester and test conditions.

Here are a few of examples of the rolling resistance test results in watts for tires from the chart I mentioned above.

  • Continental GP4000S II tire, butyl tube, 17C wheel, 120psi, 18 mph/29 kmph, 70-73F/21-23C, conducted by Bicycle Rolling Resistance (report)
    • 23C = 25 watts; 25C = 24.4 watts; 28C = 23.2 watts or a 1.8 watt reduction
  • Continental GP4000S II tire, butyl tube, 109psi, 21 mph/35 kph, wheel size and temperature undefined, conducted by Tour Int (April 2014 Issue, subscription required)
    • 23C = 22 watts; 25C = 21 watts; 28C = 19 watts or a 3 watt reduction
  • Schwalbe One tire, butyl tube, 109psi, 21 mph/35 kph, wheel size and temperature undefined, conducted by Tour Int (April 2014 Issue, subscription required)
    • 23C = 24 watts; 25C = 25 watts; 28C = 26 watts or a 2 watt increase
  • Zipp Tangente Speed tire, latex tube, 15C wheel, 120psi, 18.6 mph/30 kph, 20C, conducted by Tom Anhalt (Crr Overall Spreadsheet)
    • 23C = 23 watts; 25C = 21 watts or a 2 watt reduction
  • Zipp Tangente Course tire, latex tube, 15C wheel, 120psi, 18.6 mph/30 kph, 20C, conducted by Tom Anhalt (Crr Overall Spreadsheet)
    • 23C = 25 watts; 25C = 24 watts or 1 watt reduction

I’m sorry, but a one or two watt rolling resistance difference spread over two tires going from a 23C to a 25C sized tire is not going to make any noticeable change in your speed or time unless you are riding a TT and care about a couple of seconds difference.  What will make far more difference is picking the brand and model tire with the lowest rolling resistance.  I selected some of the best to show above but the complete chart shows as much as 5 or 6 watt differences between the more popular clincher tires.  That could mean 15 seconds or so over the course of a 25 mile/ 40K road race and as much as a minute or more over the length of a century or sportive ride.

These tests are run with tires of different sizes inflated to the same pressure to get that one or two watts of reduced rolling resistance.  Of course, I wrote earlier about how you can lower the pressure with a wider tire to improve your comfort.  And comfort is why most roadies go to wider tires in the first place.  So what happens to rolling resistance when you reduce the pressure?

Mavic claims that you fully lose the rolling resistance benefit from the wider tire when you drop the pressure 20psi.  Tests from Bicycle Rolling Resistance (see here) on a wide range of tires shows that you lose a couple watts over two tires when you go from 100 to 80psi.

How much should you reduce the pressure when you go to a wider tire?

Look at the Michelin chart above a little closer and you’ll notice that for your given weight, they recommend dropping the pressure when you go from a 23C to a 25C tire by… wait for it… about 20psi.  Ugh.  Well, at least you get a more comfortable ride at essentially the same rolling resistance from a wider tire.

So the claim of going any faster from reduced rolling resistance on a wider tire is, at best, false hope and at worst, uninformed hype.

By improving aerodynamic performance, a wheel’s 2) rim width and profile play a part in the speed you can get for the same amount of power output.

On one hand, a wider rim does put more frontal area into the wind by making any tire you mount to it wider and thereby increasing your aero drag when going straight into the wind.

On the other hand, some companies have shaped the profile of wider rims more than those making narrower ones in a way that reduces the amount of drag caused when you aren’t going directly into the wind (or 0 “yaw”).

And because you aren’t riding directly into nature’s wind, or what’s called the atmospheric wind, most of the time and you create your own apparent wind as you speed along, the effective wind is almost always coming at you from one side or another.

According to extensive field testing of road cyclists done by FLO Cycling (reported here), 80% of our riding time is spent with the effective wind coming at you from 0 to 10 degrees, 50% from 0 to 5 degrees, and only 11% of our time are we riding straight into a 0 degree effective wind. Testing done by Hambini (here), rejects the conventional approach of testing wheels assuming steady winds coming this narrow range and instead measures a more dynamic and wider range of wind speeds and directions to emulate the real world of bike riding.

Starting about 2010, HED and Zipp and other wheel makers since have demonstrated in tests of the wheels they’ve made that you can greatly reduce the drag of your wheels with a wider, deeper and U or toroid shaped rim versus those with narrower, shallower square-shaped ones.

Look back at the drawing above comparing three alloy rim widths and profiles that range from the 15C, box section profile Mavic Open Pro shown on the left to the toroid profile FLO 30 one on the right.

FLO had wind tunnel tests done to compare the Open Pro, the top, purple line in chart below against the FLO 30, the wheel represented by the red line.  Headed straight into the wind, the wider, toroid-shaped FLO 30 has about 70 grams less drag, the equivalent of 9 watts.  At a wind direction of 10 degrees the reduction in drag improves to about 155 grams or 20 watts.  Over a 25 mile or 40K distance, that drag reduction will result in a 30 to 60 second time savings.  Over a century or sportive?  Well you’ll have time to grab another sandwich and still finish ahead of your buddies riding the narrower wheels.

FLO vs Open Pro Aero Data


I’m not saying that you can’t put a toroid profile on a 15C or 17C wide, shallow rim.  Let’s just say I don’t know of anyone doing it.  It may be harder to make and you’ll also get less of an arc out of a narrower, shallower rim than a wider, deeper one.

The 3) relationship between the rim and tire width is the final consideration in determining how your speed can be affected by going wide.  Frankly, it’s the question readers ask me about more often than not.

Typically the question goes something like “Can I put a 28mm tire on my XYZ wheel?” But, I’ve also heard questions like “My budget is x. What wheel would be best with a 28mm tire?”

That second question stopped me dead in my tracks the first time I read it.  When riders are choosing wheels that will cost 5 to 10 times that of the tire that they are basing their choice on, it really tells you how strongly some feel the push to get on the wide tire bandwagon that has rolled through the enthusiast peloton.

To the first question, I almost invariably answer that if you are riding at 18mph or 29kph and faster and using wheels that are at least 40mm deep, you don’t want anything wider than a 23C tire if you want to maximize speed unless your outside wheel width is at least 28mm.  If, however, you don’t ride that fast or have a wheel that deep or you put comfort ahead of speed, go ahead with the 25C tire.

There are no wheels that are 25mm to 27mm wide and at least 40mm deep that I’m aware of where mounting 25C tires on the rims will make you faster or equally fast compared to that of narrower sized tires of the same model on the same rims.

Despite marginally improved rolling resistance even at the same inflation pressure, the aerodynamic relationship between the tire and rim has a far greater effect and favors the narrower tire.  I will try to explain why below but this drawing begins to give you a picture of what’s going on.


Source: Triathlete magazine

Simply stated, air deflecting off a tire will continue at its exit or tangent angle.  If the rim is wider than the tire, some of the air will reattach to the rim and continue to flow along the rim until it detaches from the rim as it passes by.  If the rim is narrower than the tire, less of the air will reattach and more of it will become turbulent as it passes by the rim.

The wider the rim is relative to the tire, the greater the amount of air that will reattach and the less the amount of turbulence.  The greater the distance between the air passing by the rim and the rim itself, the greater the amount of turbulence.  More turbulence creates more drag.

HED patented the relationship between the tire and rim widths including the angle of the rim where the air coming off the tire first re-attaches.  This allows them to design wheels to excel across the range of yaw or effective wind direction the rider will likely see for the type of riding or event he or she is doing.  In the drawing shown taken from the patent application, you can see the central role of different tire widths (440’, 440”, 440”’) and its relationship to the rim angle (465) at the point where the air would reattach.


Source: HED cycling patent filing

Source: HED cycling patent filing

The toroid rim profile and rim length are covered by a patent that HED first developed and licensed to Zipp around 2009  that was central to the Zipps successful Firecrest line and caused other companies to move away from the box and V-shaped profiles they had used for years.  While many leading wheel manufacturers have adopted angled brake tracks like those you see in these drawings, Specialized is the first company to license this newer HED patent.

So, as you can see, the relationship between the tire and rim’s width, along with the rim’s profile and depth, have a great effect on your wheel’s aerodynamics.  While the leading wheel designers including HED, Zipp, ENVE, and Easton have their own design teams, all of these companies recommend you use tires narrower than the brake track width of their rims.

Most of the leading wheel companies designed their toroid shaped, carbon rims which have a 25mm or wider outside width around 23C tires and their 28mm or wider outside width rims around 25C tires.  Of course, many of the best 23C tires (often labeled 23mm) actually measure between 24mm and 25mm wide when mounted and inflated depending on the tire model and rim size it is mounted on. Likewise, 25C or 25mm labeled tires usually measure 26mm or 27mm wide.

In the case of Easton’s EC90 Aero 55, they recommend an even larger tire-rim width difference.  Easton’s 55mm deep Fantom wheel rim has a 19mm inside width, a 28mm outside width at the brake track and has a 29.5mm maximum width at the at top of the arc of its toroid shape.  As you can see in the chart below, 21C and 22C tires generally performed better in their aero tests compared to even 23C tires and certainly compared to tires of the brand and model.

Easton Fantom Tire Tests

Source: Easton Cycling

In the case of the same Zipp Tangente clincher tires used in these tests, the 21C bested the 23C version by 60 grams of drag which equates to 7.8 watts and 23 seconds savings over a 40K TT at 30mph/48kph.  (The time savings will actually increase if you don’t ride that fast.)

Of course, alloy wheels aren’t as wide, deep, rounded or angled at their brake tracks as the carbon wheels made by Easton and others are.  However, the findings that tires and rims work together to determine aerodynamic performance and favor tires narrower than rims are applicable to carbon or alloy wheels.


A wider tire and a wider rim together can provide better handling.  The wider tire provides a wider “contact patch” than on a narrower tire.  While the area of the tire patch for both tires is the same as long as your weight and the tire pressure is the same, that area spreads further across the width and less along the length of a wider tire.

The wider contact patch on a properly shaped and supported tire is what gives you better handling when road surface, moisture, tire inflation, and speed are all the same.  While handling seems like a highly subjective property, Tour magazine – the highly analytical German cycling review publication – actually ran tests using a stunt rider to test and establish tire grip ratings.  While the wider contact patch = better handling claim makes sense and tracks with many enthusiasts experience including my own, I await quantitative evidence of how much better the handling is going from a 23C to 25C or a 25C to 28C tire.

Continental use the handy (and frequently seen) chart below to show contact patch differences though, as discussed above, their headline conclusion about rolling resistance is technically correct but insignificantly small (and doesn’t warrant one, let alone two exclamation points) to the average roadie.

Conti contact patch chart

Now if you reduce your tire pressure on the wider tire to get more comfort, you’ll get a even wider contact patch than on the wider tire inflated to the same level as the narrower one.  So you’ll increase both the width and area of the contact patch relative to the narrower, more inflated tire you used to ride.  This is part of what improves handling.

The other part of the improved handling comes from a wider rim.  The wider rim sets the foundation for the wider tire to better keep its sidewall shape as you can see in the drawing on the left.



The problem comes when riders, having read about all the benefits of wider tires, mount a pair that’s too wide for the 17C or 19C wide alloy stock wheels that came with most of our new bikes or the upgrade alloy rim brake wheels sold by most of the leading wheel makers for the last 3-5 years.

A 25C tire on a 15C wheel can feel squishy, even more so if you’ve reduced the air pressure to get more comfort.  This squishy feel is a symptom of the tire losing its shape and its tendency to fold back on itself.  This is the opposite of the improved handling you are looking for by going to a wider tire.

In the worst circumstances, a tire that’s too wide for its rim can experience a Type 1 pinch flat when you are cornering at speed as shown an earlier drawing or the tire bead can pull away from the rim hook, also resulting in a flat.  Not good, to say the least.


So what combination of bike tire and wheel sizes are best for you, my fellow road cycling enthusiast?

The tire-rim width chart in the ETRTO standards manual says a 15C rim can safely use tires from 23C all the way up to 32C or mm in width.  If you look closely, it also says that you should use nothing narrower than a 28C tire on a 19C rim and a 35C tire on a 21C rim.

Modern rim brake wheelsets for road bikes range up to 19C with a few up to 21C.  Most road disc wheelsets are no wider than 21C.  None of the companies that make these wheels recommend putting 32C or 35C tires on their wheels.  Further, few rim brake road bikes will fit a 28C tire between the rear stays.  Likewise, few road disc brake bikes will fit a 35C tire.

The ETRTO standards also say nothing about the speed, road surface, tire type or tire pressure conditions you are riding under.  A mountain biker bouncing along on knobby tires inflated to 40-50psi on a dirt trail going at half the speed of a roadie leaning into a fast corner on a smooth road with tires pumped up to 80-100 psi are experiencing very different situations.  And it hasn’t been updated as road wheels have gone through a couple generations of major changes.

The chart is a guide that needs to be updated or tossed when considering the real world that road cycling enthusiasts live in today.  Wheel and tire makers have been holding meetings to update it for years without agreeing on new set of standards while trying to get bike manufacturers to widen the spacing between the chain and seat stays and the front forks.

Meanwhile, most wheelset companies recommend an appropriate tire width for their wheels.

Here’s my take on what mix of comfort, speed and handling you can expect with different tire-rim combinations.

A 23C tire on a 15C wheel – this is the likely stock or alloy upgrade wheel and tire combination you have as a baseline on bikes made before 2016. You know how it rides. This is still a perfectly good width combination in my view. What follows are your options.

A 25C tire on a 15C wheel – somewhat improved comfort over a 23C tire but worsened speed and handling for reasons described above. Better to reduce pressure 5psi or so on 23C tire for better comfort without losing handling performance. Neither combination is going to be an aero star.

A 25C tire on a 17C wheel – better comfort but no better speed or handling than a 23C tire on a 15C wheel. 23C tire on 17C wheel at right pressure will get you somewhat improved comfort with improved aero if the rim has at least a rounded nose rather than box or V profile, is >35-40mm, and you are riding at 18mph/29kph or faster.

A 25C tire on 19C or 21C wheel – better comfort, improved speed and handling over options above. A nice set-up for long endurance rides at a good average speed (18mph/29kph or higher) especially on deeper (>35-40mm) and preferably rounded profile wheels. But, most alloy wheels aren’t going to be that deep or have a rounded rim profiles where the spokes join the rim.

A 23C tire on a 19C or narrower wheel – best speed. If you’ve chosen this set-up, crits, road races or TTs and triathlons are probably your passion, deeper aero wheels are probably your preferred hoops and comfort is further down your list of what matters though there are plenty of wheelsets in this width that will be plenty comfortable to start without the need for a wider tire.

A 28C tire on a 19C or 21C wheel – best comfort but at the expense of speed if you put them on a deeper aero wheelset. There’s also a likelihood that the tire – which will likely measure 30mm or wider – won’t fit between the rear stays of your rim brake bike and earlier model disc brake bike.

A 28C tire on a 17C or 15C wheel – handling could be seriously compromised with this combination. You are also likely to get an increased number of pinch flats. Also, as with the combination above, it’s likely the tire won’t fit between the rear bike stays or inside your rim brake calipers.

* * * * *

Thank you for reading.  If you’ve made it this far, congratulations and please let me know what you think or ask any question in the comment section below.

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Enjoy the ride!

First published on April 3, 2016 but updated regularly since as new wheelsets and tires have been introduced. The date of my most recent major update is shown at the top of the post.


  • Grahame Lancaster

    Hi Steve,

    been ploughing through your articles which are great and easy to read, hope you might point me in the right direction.

    Have pair of mavic Mavic – Cosmic Carbone 40C , few years old now been retired from sale I think

    The specs ( state

    etrto 622x13c (19-28mm tyre size)

    I have terrible problems with grip (wheels locking up under breaking, also not very grippy)

    I ditched the ykison mavic tyres and used shwalbe one’s 23mm which improved things a bit, but still very sketchy compared to my standard mavic cosmic carbones running the same tyres and pressures (wider alu rim I think).

    My gut suggests the issues may be to do with the narrow tyre bed – have you any thoughts on this?, feels like a pram wheel at times.

    I was going to try a 25mm/28mm but am concerned its too wide to be safe despite what the specs say, not too worried about speed sacrifice at moment.

    would wither a 25 or 27/28 be worth a go, otherwise I’m looking at selling the wheels, which cost an arm and a leg!

    • Grahame, If you have a problem with wheels “locking up”, probably be time to get new brake pads and make sure they are aligned well. If you want better handling, go with a narrower rather than wider set of tires than you have now for the 13C wheels. 25C or wider tires will make the handling worse. I’d suggest Continental Grand Price 4000s II in a 20C size. That vintage Yksions weren’t very good for handling and grip. At some point you’ll want to go with wider wheels to get more comfort and better handling. Steve

      • Thanks Steve, I did take the bike back to the LBS and they toed in the brakes and new mavic supplied pads but not much difference. Ill def try the conti tho and have an eye on getting some enve wheels. thanks for help, much appreciated.

  • I laugh at all the BS on tyres, the “technology”, etc,I raced on singles/tubulars and high pressure/clinchers for training. The choices were no where near as extensive as now.

    What is blinding people I feel is a couple of factors, the aero effect, in real riding, how often will you have a direct head wind? I would say sometimes but the road changes direction and then?? Riding with the effect of buildings and trees etc changing air flow around the bike, other riders around you so looking at pure aerodynamics is a Utopic myth unless you are circulating around a indoor velodrome.
    So what is the real aero effect gain?? Nowhere as much as we are led to believe.
    Handling and bike compliance with added comfort is a real time effect in every condition and situation so that’s where I feel the effort should be made.
    Being in my prime in the mid 80Kg bracket (80s into the early 90s), I excelled in cornering, descending and pave, why? The bike worked with me to do this, the trend then was to go 23mm tyres and even 21mm pumped to 120psi and more, while I was on 28mm at 100psi or less, a supple tyres melds with the road surface with better handling/cornering hence faster riding unless all you do is ride TTs on a strait piece of road with a direct head wind..

    Put rounder tyres on, enjoy your bike and stop being a aero-weeny and enjoy the ride

    • Lb, Aero performance is not about the the frontal surface width of the tire. Rather, it’s about getting the air coming off the tire to continue to flow along the rim and increase the lift/reduce the drag of the wheels. If the inflated tire width is wider than about 90% of the rim width at the brake track, the wind is going to separate or at best create a turbulent flow at the intersection with the rim.

      Think about an airplane wing. If the leading edge of the wing was wider than the section behind it, you wouldn’t get nearly as much lift as wings where the width gradually increases from the leading to trailing edge.

      With today’s wheels being deeper, there an opportunity to continue that attached flow a lot longer than with the shallower wheels you may have raced on so you can get a lot more lift. And while direct head wind happens a small percentage of the time, wind coming within +/- 10 degrees of straight on happens most of the time. With wheels less than 30mm deep or speeds less than 18mph/29kph it matters little due to the exponential aspects of the aero equation. In those cases, handling and compliance/comfort play a more important role in your tire width decision. Steve

  • Hi Steve,
    I have Hed + rims 25 mm outside , 20.7 inside . I run tubeless Schwalbe Pro One 23 mm tires as they measure 26 mm on this set-up and my bike will only take 27-27.5 wide tires for 2 mm clearence at the chainstay.
    I think this tire runs wide and I would like to know if anyone has promoted using the o-o edge ,lay flat measurement as a way to tell if a tire will fit and what the tire might inflate to on a given rim.
    For example:I now know that a Schwalbe ProOne tubeless 25 measures 70 mm wide laying flat and is 28.5 when installed and inflated. The same tire in 23 mm is 61 mm layed flat and measures 26 mm inflated.
    I think A tires installed width could be determined better this way.
    I really enjoy your articles.
    Thanks, Dave

    • Dave,
      Rim inside width and tire pressure both affect the mounted and inflated tire width. I don’t see how the o-o measurement would address this.

      I’d also encourage you not to run a 23C tire on your 20.7mm inside width HED. That’s going to be a far less comfortable set up than a 25C and, more importantly, it’s not a terribly safe set up. The stretching you get will make the tire height less which will make the handling worse and will also run a greater risk of the tire pulling away from the bead. You should also have at least 4mm of width between your tire and chainstay to allow for wheel deflecting. Watch this video from Ben Delaney at Bike Radar to see how much deflection you can get. Get a bike with a wider chainstay or use a narrower wheelset.

      • Steve,
        Your recommendation seems contrary to thesdvice on your site, where you recommend 23 mm tires on these and similar wheels. Your thoughts ,if I read them correctly, were that 23’s would give a better shape , thus handling and speed would be improved. I think you recommended the very set-up I have.
        My bike is a Moots CR and I love it, so I won’t be chamging it, but I would change wheels if nessesary.
        With the 23’s mounted I have 3 or 4 mm clearence at the chainstays and the tires measure 26 mm.
        I can’t run 25 mm tires as they measure 28.5 when on my wide rims and only leave about 1.5 mm clearence at the chainstays.
        With all this info. I’d really appreciate your advice for my particular bike.

        • Dave, you are right and I’ve now modified my recommendation about 23C tires on rims >19C. While I do think 23C tires are fine on 19C rims, I don’t think you should run 23C tires on rwim ith inside width of 20.7mm (or over 19mm) because they begin to stretch too much to comfortably and safely handle high speed cornering maneuvers.

          There are tradeoffs and crossover points. Wider tires are more comfortable as long as they aren’t so wide relative to the rims to increase pinch flats and aren’t so underinflated to create squishy handling. However, wider tires are less aero than narrower tires if their mounted and inflated width is greater than the outside width of the tire. For people who have low profile rims or who don’t care about speed, aero is nothing. Narrower tires will handle fine on narrower rims but narrow tires on wide rims are going to handle worse than wider ones and at some point the handling will be, IMHO, considerably worse and high speed cornering can become problematic.

          In your case, 25C tires is what I’d suggest for the 20.7mm internal width HED rims. But for your Moots, I’d suggest a 19C or 17C wheelset with a 23C tire that will expand to no more than 25mm for your 30mm (?) min chainstay width. Note that different tires will measure different widths on the same rim. For example, I measured 23C Zipp Tangente, Michelin Pro 4 and Conti GP4K tires at 24.7, 25.0 and 26.0mm respectively at 100psi on the same Easton EA90 19C rim measuring 19.5mm inside rim width. These tire widths will also increase as you run the tire at lower inflation pressures and as the tires age. Steve

          • Steve,
            I am going to buy new wheels per your suggestions.
            Could you recommend some alloy and carbon wheels in the 17-19 internal width ?
            These wheels would be used for every day , mountain trips, 100-150 mile rides/events.
            I don’t road race anymore , bur I love to go fast, and I do competitive group rides.
            Thanks for all your help.

  • I should add that I do like tubeless wheels , but I am not locked into them.

    • Dave, take a look here for alloy and here for carbon all arounds. While you probably don’t want to hear this considering how much you like your Moots, you might want to consider a new bike with more modern chainstay dimensions (and other features) to better fit your current, perfectly good HED wheels. Steve

  • Hi Steve, I’ve just bought a Specialized hybrid with 21c rims fitted with heavy 30 tyres. I’ve always been keen on Conti tyres and would like to fit some 28 Gatorskins. The ETRTO site suggests at least 35 tyres on these rims !! The 30’s look enormous . Knowing that it’s entirely up to me from the safety angle, how about these 28 Conti’s. Cheers, Nev

    • Nev, Hybrids are a whole different game than road bikes. If you are going to be riding off road, you want wide tires, perhaps tubeless. Aero is irrelevant. Wheel size often different than road wheels. Frame geometry definitely is. You can’t extrapolate off-road handling and comfort from what I’ve written above. Steve

  • Another awesome review, Steve. Thanks! My top tire priority is safety and my main concern as an urban rider is getting caught in seams in the pavement. This seems a little different than what you refer to as “handling.” I would think that a fatter tire would be safer in this respect, but I’m not sure if this thinking is correct. Do you have any thoughts on this?

    Pending your response to the above question, I have two bikes: One with 13mm rims and the other with 17mm rims. If I extrapolate your recommendations above and want to prioritize handling, I’m guessing you’d say to go with 20-23C on the 13C rims, and 25C on the 17C rims. Am I on the right track? Thanks!

  • Hey Steve, Norwegian fan here!

    I have a 90 km “timetrial” this summer, including 2x1000m of ascent AND descent. Given the profile aerodynamics is not my main concern on this route. I have decided to use my standard race bike, and i have a pair of FLO 30 wheels that I belive will be my best choice. The reason for this is because i belive the wide profile will help me with a safe and quick descent, and that the 200 grams I would save by using by DT Swiss R21 Dicut wheels would have a smaller impact.

    I have then 2 questions for you:

    1. On the wide Flo30s would you recommend 23c or 25c tires (probably GP Conti 4000 IIs)
    2. Should i rather switch to the DT Swiss wheels

    Thanks for your help!

    • Hello Carl, I must tell you that I am a fan of Henrik Kristoffersen and Aksel-Lund Svindal!

      My answers are
      1) 23C
      2) No


  • Hi Steve, currently I run 23mm GP 4000S II on 17C with 4.5/5 bar (less feels squishy). Could I reduce the tire pressure for another 0.5 bar with 19C rims and my 70kg?

    On my other bike I run 25mm GP 4000S II on 21C rims and 4/4.5 bar which is a lot smoother on very rough roads. But these won’t fit in my first bike.

    • Charlie, 4.5-5bar (65-73psi) is way low already for rider your weight for tube & tire set up on the road. I’d think the handling would be pretty squishy already and you’re apt to get more pinch flats. I’d actually raise it on your 17C wheels for better performance. See here for more

      • Thanks Steve, yes this is the absolute minimum and with another tire this would be too low, but the “hard” 4000S II takes it without a noticable higher rolling resistance, still good cornering and no flats so far. With a Vittoria or Veloflex tire this would be an issue for sure.
        There are a lot of very rough tarmac roads around here, and there is much more vibration from the tire with 5/5.5 bar. I am spoiled by the 25mm tire on 21C and it also feels faster on rough roads, too. But my Cannondale Evo 1st gen, only takes real 25mm in the back, so the only chance without changing the frame would be a wider inner rim. But if an even more reduced pressure wouldn’t make sense with 19C, then I have to stick with what have. It’s complaining on a high level. 😉

  • Hello Steve, I’m not a long time follower… in fact, I just found you online!! In the short time I’ve browsed your reviews, I’ve come to respect your POV. I could use some help deciding on a set of wheels.

    I’m in my 50’s, do a couple of 40+ mile rides per week, have an ’06 Litespeed Siena Ti bike (yea, I know… it’s awesome!!) on Ultegra 10/sp, am 185lbs, don’t race, live in hilly San Diego and find myself in this dilemma….

    It would be nice to replace my circa 2002 Mavic Ksyrium Elite wheels. They’re straight, work well, but narrow (15mm internal). I’d like to try some 25C tires…. Plus, I just want something new!!

    I found a great deal on the 2014 version of the Easton EA90 SL for $375, delivered from a reputable LBS. These are the 17.5mm internal/22mm external width wheels.–2014-wheels

    Should I pick them up or are the improvements of the newest 2mm wider wheelset worth the extra $500?
    Of course, if you think I should look at something else… feel free to suggest.


    • Jay, I’d measure the width between the front forks and rear chainstays to make sure a 25C tire is going to fit. A 25C tire on a 17C or 19C wheel is going to measure 27mm or so and you want another 5mm either side of the tire for lateral bending when cornering. So it’s best if you have 40mm or so of width in there. You’ll also want to see if your caliper brakes will reach that far without having to replace the cable and even if they do whether they are going to give you enough leverage or will close more like an A than an upside down U on around your brake track. That may be the biggest limitation. If the 17C wheelset and 25C tires will fit, I’d think that’d it wouldn’t be worth spending an extra $500… or at least I wouldn’t. On the other hand, if there’s room in the frame and it’s still in good shape, you might want to consider upgrading your groupset ($600 for an 11-speed Ultegra 6800) to replace what may be some old/worn 53/39 chainrings and help that 50yo/185lbs guy get up hills a little easier by moving to a 50/34 chainring with an 11-28 cassette. Then going to an 19C wheelset like the new EA90SL would be worth it and a 17C would have been a mistake. Improved comfort going from 15C/23C to 17C/2C whee/tire is highly dependent on the compliance built into the wheel and not just the wider tire. Some wheels there’s little difference when they step up, some there’s a lot. Steve

      • I appreciate your insightful response, Steve. It looks like I’ll have plenty of room for a 25c tire. As for the brakes, they will certainly retain the “U” shape you eluded to..

        I installed a new, full Ultegra 10 group last year. Compact crank, 11/28 cassette all still in excellent condition so I don’t think I’ll be replacing it in the near future. I’ve been happy with my selection as there is very little flat land here!

        I decided to pick up these wheels because they HAVE to be an improvement over my circa 2002 wheels (unless you believe them to be inferior or know of something else I should pick up).

        I just read your tire recommendations and am a bit puzzled. My intent was to run 25C Continental Grand Prix 4000S II’s but you state not to use a 25C/25mm size Conti tire unless the wheels are 27mm or wider at the brake track, I believe the brake tracks are 22.5. Can you clarify please?

        Again, thanks so much for your time and effort!!

        • Jay, The 25C will be fine for what you are trying to do – not racing, shallow wheelset, comfort a priority over speed. Steve

  • Dear Steve,

    like Dave I have been happy with 23mm tyres (GP 4000S II) on HED plus clincher rims 20.7mm inside width. HED recommend 22mm+ tyres on the HED plus clincher rim. Have you ever seen “high speed cornering maneuvers” result in accidents with narrow tyres on wide rims?


    • Andrew, No, but I don’t go looking for bike accidents. I’ve had a couple of my own and that’s quite enough thank you. I wouldn’t recommend 23C Contis on 21C rims unless you are going in a straight line or taking very wide turns. Very aero on deep rims intended for TT or triathlon type courses (and that my be the context in which HED may have recommended them) but neither comfortable or good handlers on all-around type riding and limited/no benefit on shallow rims. Steve

    • I would second Andrew’s comment here. Been racing and riding for 15 years on clinchers and tubulars, the HED 6 black have given me no problems with 22mm conti attack front and 23mm conti 4000S II. On the contrary: hey feel super grippy and predictable when cornering. The tight fit on the rim (tubeless) would seem it almost impossible for issues to emerge there I would think.

      I did enjoy reading the article here, but was curious about the whole element of hysteresis/vertical losses that happen in real conditions compared to running a smooth drum. I haven’t seen a convincing analyses on that, but my sense is that unless the surface is super smooth (more often not in my part of the world), the whole 120 psi efficiency does not really apply any more and a softer/wider tire would be the faster choice as the vertical losses (think cobbles in the extreme are significantly larger than ideal conditions rolling resistance. Curious to hear your thoughts on this or if some testing has been done on this quite complicated topic. Ron

      • Ron, haven’t seen a convincing independent analysis on this point either but there is a lot of analysis done by a tire maker and pump maker that says you should ride the widest tire you can at the lowest pressure you can to overcome the energy losses from the tire and power losses from the tired rider who is also absorbing the road effects. Unfortunately, these analyses, in my view, don’t take resulting aero or handling changes created by wider, lower psi tires into consideration.

        That said, don’t know anyone who rides tires at 120 psi anymore. Steve

  • Steve,

    Very informative and well-written article. I am wondering if you can help me with the following. I am considering a wheel upgrade and unsure if the new wheels will fit my? frame.

    I currently run 23C tires on a 15C rim (Conti 4000s on Shamal Ultra rims which according to Campagnolo specs are 20.5mm wide). At the widest point of the tire, these leave a few mm’s on each side (between tire and fork) maybe 3 or 4 at most, on each side.

    I am considering buying Campagnolo Bora One rims, which are a 17C rim and 24.2mm wide, as per Campagnolo.

    If I mount the same 23C tires on those 17C rims, will they be wider than my current setup of 23C on 15C rims and if so, by how much? Do you think they will fit?

    • Rob, Looking back at my measurements of different 17C wheels with those 23C tires, you are likely to get an inflated tire width of 24.5mm +/- 0.5mm. You want about 5mm either side of the tire to the forks and stays to allow for wheel deflection in turns. Don’t know what the tires measured on your Shamal’s but I think you might be cutting it a tad too close my friend. Steve

  • Great and helpful information especially for novices like me, so thank you. I’m hoping to get some additional confusion cleared up if you are still monitoring comments. I keep searching around and still have no clear answer.

    In the article, it seems to make it clear that the rim size (15C, 17C, etc) references the inside width in millimeters. For instance, it is described that common road bikes come with “wheels that are designated 15C or are 15mm wide between the tire bead hooks”. I understand the “C” to be the fact that the rim has hooks or “crochets”.

    So, here’s what I don’t understand. I’m looking to purchase one of the lower tier Fulcrum models from Racing 7 LG up to Quattro LG. All claim a wider rim and use of a minimum 25C tire. But, the descriptions I see for these rims indicate they are only 17C. The spec page on Fulcrum’s website confirms with “23,2 mm, ETRTO 17C”. However, I can easily see 622 x 20.5 printed inside the rim in pictures on the same page ( So, I’d expect the 20.5 to be the actual mm width and thus they be would actually be 20C, right? What am I missing?

    Bottom line, I’m after this combo:

    “A 25C tire on 19C or wider wheel – best comfort, improved speed and handling over options above. A nice set-up for long endurance rides at a good average speed (18mph/29kph or higher)”

    Thank you!

    • Rob, This numbering system is anything but clear, so I totally understand the confusion. The C designation for wheels is based on the inside width across the bead hooks. On tires, it is based on the outside width as mounted on, I believe, 13C or 15C wheels when this whole crazy system was developed. The actual mounted and inflated tire width on today’s wider rims is much wider than the actual C designation of the tire.

      I don’t believe Fulcrum make any wheels in the price range you are looking at wider than 17C. Most companies don’t. Not sure what the 20.5 refers to in the photo. Perhaps the rim tape width. The Quattro is clearly a 17C wheel that apparently is 23.2mm outside width, at the brake track.

      Here’s my review of wider alloy wheel upgrade choices. Unfortunately, they are more expensive than the Fulcrum Quattro and Racing 7.

  • Hello Steve. I am from Portugal. What are the best tires and width for the Bontrager Aeolus pro 3.

  • Hi Steve, great article!

    I had a local bike shop build me a new wheelset using the Boyd Altamont Lite rims. You’re probably familiar with the specs of the wheels so my question is, what are the ramifications of riding tires that measure closer to 27mm, 28mm or even 29mm when mounted? I

    I’m currently using my older 23C tires from when I had 15C inner diameter wheels. My current front tire (Michelin Pro4 SC 23C) measures 25.15mm wide and 21.41mm tall at 70PSI and the other (Conti GP4000S II 23C) measures 26.6mm wide and 22.79mm tall at 85PSI rear wheel.

    I picked up a few tires to test mount. Two Corsa G+’s at 28C and 25C and the newer Michelin power competition in 25C. In that order, and in width and height by mm, the tires measure 29.10 x 25.5mm, 27.28 x 23.7mm and 26.78 x 23.00 after letting them stretch for 48 hours starting at 75 PSI.

    I’ve factored in deflection and my frame will not have issues running 28C tires.

    If my priorities are more towards comfort and reliability but still would like good speed to hold on to wheels in fast group rides (38-40kph), which would you recommend I use? Thanks!

    • Karl, As I lay out in my post, tire and rim size need to be considered together when prioritizing speed, comfort and handling. And I did evaluate the Boyd Altamont in my review of the best upgrade wheels for rim brake bikes here For those reading along, I measured the Altamont front rim at an average of 19.7mm wide internal, 24.7mm wide external and 25.0mm deep and the rear at 19.8mm, 24.3mm and 25.1mm. FWIW, I take 4 or 5 rim and tire measurements at different points around the wheel to come up with an average as there can be quite a variance due to rim manufacturing tolerances and the effects of pressure. I always measure tire at 100psi just as a benchmark though they will be marginally narrower at lower pressure.

      Also, as your measurements indicated, tires with the same C or mm rating (like 25C or 25mm) can measure a mm or two narrower or wider than another of the same rating made by a different manufacturer. And some will measure differently than tires made by the same manufacturer. So Conti GP4KSII measure wider than Mich Pro4, Mich Pro4 measure narrower than the Mich Power Competition that replaced it (the Conti GP4KSII and Mich PowComp measure about the same), and the Zipp Tangente 25C actually runs narrower than the same tire in a 23C. And, of course, all the sizes are useless if you are comparing wheels of different rim widths. The whole tire measurement scheme was developed years ago around 13C wide rims. One of the road wheels I’ve been testing this summer has a 25C rim. One 28C tire I put on it measured nearly 33mm wide, another about 30.5. With this in mind, I find the whole hype around 25C tires and wider tires, in general, more than a bit ill-informed on the part of the hypsters (ie. tire makers, reviewers and sellers).

      OK, onto your question. If your focus is on comfort, go with wider tires and lower pressures. Recognize though that as you get wider and lower, you will reach a point where the handling will get worse than with a narrower tire or with a higher pressure depending on width and pressure in relationship to your rim internal width. And you’ll also reach that point where you’ll be more likely to get pinch flats rolling straight or in cornering. For the relatively wider Altamont rims, I’d expect you would be fine with 25C Conti 4KSII or Mich PowComp at 75psi if you weigh up to about 175lbs. You didn’t mention your weight, which is a critical factor in determining tire pressure and performance. I weigh 150lbs around this time of the season and don’t run any tubed tire 25C below 75psi. When I do, I lose road feel and my handling gets mushy in the turns. I do run 28C tubeless tires down to 65 psi but that’s a whole different ball game. If you weigh 175, I’d think 75psi would be the lower limit. If you weigh closer to 200lbs, I wouldn’t go near 75psi. Anything wider than 27mm mounted and inflated to 75psi on that rim would probably start to give lower performing handling. I wouldn’t suggest anything wider than the widest measuring 25C.

      Comfort, by the way, is also a function of the vertical compliance of the rim. Much of the push to 25C tires was to make up for the lack of compliance in many rims. You can improve the comfort of a less compliant rim by lowering the pressure in the tire or putting a wider tire on, but only so much. Likewise, a compliant rim is going to be comfortable with all but the highest pressure tires (like 110psi). As you can see from the chart in the post where I reviewed the Altamont, it’s compliance was on par with most of the wheels in that review.

      As to speed, low profile wheels like the Altmonts, regardless of the tire width, aren’t going to help you go faster. Tire rolling resistance will help you somewhat but not enough to notice by changing width. I detailed in the post above the roughly 1 watt of rolling resistance improvement as you go from 23C to 25C to 28C as a rule of thumb, but it’s not always the case. The bigger difference is between tire models, e.g. a Conti GP4KSII will have much lower rolling resistance than a Conti All Season or Gatorskin tire. All the tires you mentioned are in the same general performance tire class so have lower rolling resistance. The GP4KSII and PowComp are among the best.


      • Thanks for the detailed response Steve.

        I will use tires that measures 26-27mm then regardless of its printed “C” rating. I forgot to mention that I weigh 143lbs pretty consistently. Not too far off from your 150 so I’ll go with your suggestion of not running any 25C tubed tire under 75psi.

        What about tire height? Is there a sweet spot there?

        As usual, very good and valuable information to me so thank you for taking the time!


        • Karl, Ok. At your weight you might be able to get down to 70psi without issue. I ran some 28C Pro-One tubeless at 70 psi front, 75 psi rear on some 25mm internal width disc brake road wheels (ENVE 4.5AR) Saturday and loved them. Those were tubeless however, so no concern for pinch flats.

          I really don’t have much insight into height. That’s a blind spot for me. I think it marginally affects speed (taller=faster) rather than comfort but don’t know by how much.

          On the subject of how to ride faster, I’d encourage you to read the two posts I wrote on that subject here: and here: I learned more about how to ride faster doing the research for these posts than from all my evaluations on wheels and tires.

          Now if I could only stay on my training program, I actually would ride faster! Steve

          • Lovely wheels those ENVEs! I remember Si at GCN had a video on those wheels and tire combo and I was drooling.

            Ok about the height. The differences seem minimal anyway (1mm or less between 25C models)

            Thanks for the reading material on riding faster. I took a quick glimpse and will add to my to read list. Best of luck staying on your training program Steve! Thanks again


  • By far the best article on this subject I have read. I’m a budget rider as I don’t race etc. Average in the 15-16mph range for my 30mile ride with hills. Have a set of 2014 Fulcrum 5 wheels. Had Serfa Seca wire bead at 23mm, but reading all the hype on 25mm it got to me so much I had to have them. Went with Michelin Lithion II tires (again a budget tire, but with great reviews). Max PSI on these is 109 (Secas at 125psi, used 120 on rear 115 on front). Lithions felt like utter crap. Handling was bad, felt like I was cycling through mud, could feel the rear tire move on me to where I thought I had flats. Went back to my Seca’s and all was well. Now stepping up to 120 TPI with 70a center and 58/50 side durometer i.e Serfas Heylix (like the Serfa brand!) – in 23mm as I won’t go back to 25mm. I thought I must be the only seed in the fold that preferred 23mm, so went searching online and found this article. Answered most all my questions. Glad to know there is some science to back up my experience and a pro actually stated a 15c rim should have 23mm – I’m not crazy and can sleep well. Thank you!

  • Tubeless really seems to throw a wrench in that Michelin tire pressure chart. I’m running 28c Schwalbe Pro One on 18mm-internal rims (the tires inflate to 30.5mm and 31mm), and at 175 pounds in gear on a 20-pound bike, I’ve settled on 45 PSI in the front and 60 PSI in the back. I used to run 65/80 for lower rolling resistance, but that benefit reverses if the pavement or path is anything less than pristine. Michelin’s 90 PSI recommendation would be truly unpleasant. And I’m not even close to bottoming either tire; I could drop another 10 PSI on both sides without any fear of rim damage.

    If we assume the tire shouldn’t balloon wider than the rim’s width at the brake track, there’s almost nothing on the market that seems appropriate for 28c tires. (Enve’s 25mm-internal AR rims seem about it.) It looks like 25c on a modern, wide rim is the sweet spot for comfort and rolling resistance. The aero seems to be a wash relative to 23c if the rim is correct.

    As much as I am proud to come from a country of innovators and inventors, I feel ashamed that a tire manufacturer from same country routinely resorts to blatant lies and half-truths, to sell their products. Yes, I’m talking about the company that claims they have 180tpi (with 3 combined layers of 60tpi, that’s the part they don’t advertise).
    With narrow tires being associated with high-performance, and wider tires with leisure bikes, tire manufacturers saw an opportunity to grow revenue with existing products: change the perception of wider tires, increase demand, and price rises will logically follow.
    Now don’t get me wrong, I have nothing against wider tires. In fact, I like them. I’m 6ft2 and 190lbs, and it just doesn’t make any sense for me to ride around on tires with a 19mm cross-section.
    We’ve seen a slew of articles lauding the merits of wider tires: “lower” rolling resistance, “increased” grip, better comfort, etc.
    The truth is, that all of the comparisons I have seen were done with either the smaller tires under-inflated, or the larger tires over-inflated. The comparisons are done wrong. Over-inflate a narrow tire, and rolling resistance will decrease. Yes, tire flexibility has a lot to do with it, but so does pressure. None of the comparisons are being done correctly. This is partly due to the fact that advertising revenue comes from the manufacturers, and the magazines and websites, essentially staffed by journalists and not engineers, drink the cool-aid served to them… and they won’t do too much questioning, because doing so would cost then ad-revenue.
    Another blatant lie, or piece of propaganda if you prefer, is the contact patch in the above Conti diagram. Those two tires have the same inflation pressure. Once again, it’s done wrong. An 80kg rider, on a 23c inflated to 120psi, or on a 28c inflated to 80psi, will have _very_ similar contact patches on the road. But pf course, that’s not how they do the comparisons, because it wouldn’t show the fatter tires in an as-advantageous light (keep in mind, their goal is to increase the value-perception and increase prices of larger tires).
    Another MYTH: wider tires handle better. While going straight, bigger tires probably handle better. And with the lower PSI, they will conform to surface asperities better than thinner tires, thus having better efficiency on rough surfaces and providing a more comfortable ride. BUT… they won’t corner better. Take an eraser. Place it on a table. Push it. Pretty easy. Now place a weight on it (or press down on it), and try to push it. Not so easy anymore. This is a very simple way to illustrate how, the more weight you have on a smaller surface area, the more it grips. Telling us (erroneously, I remind you) that a larger tire has a larger contact patch (especially if you do the comparison at incorrect relative pressures), therefore has better grip, is a total fallacy! A thinner tire, with more of your weight on a smaller area, will grip more any day. Even on wet pavement, because there is a smaller area from which to displace (push to the sides) any water, so that it “slices” through to make contact with the pavement better than wider tires can.
    If you are racing, stick with your racing tires. If you are training or riding for pleasure, go ahead and save yourself a little torture, and get wider tires.
    But if you do, get an additional set of wheels. Because you will want wider rims, if you like to corner fast.

    • PS: “Over-inflate a narrow tire, and rolling resistance will decrease.”
      Same goes for over-inflating wider tires. Hence their better showing.
      (should have put that in)

    • That’s interesting read so far, thanks for your informative posts, I really learn from your posts.

      Somehow, why pro road racer grand tour level opted to go with 25 standard and not 23 anymore?

      I understand there some race-stage they will rodes on cobbles and needs more beefer tryes

      This seems to affects everyone included me, I go for wider tryes because there many benefits and *ahem* pro race on 25 these days

      • Adette, Pros race on tubular tires which run truer to size and they also ride the latest, wider rims. So for them, there are no aero losses. Most of the rest of us ride on narrower, clincher rims on which 23C tires measure 24-25mm once mounted and inflated. If you put 25C tires on 17C clincher rims, you are riding tires that are 4 or 5 mm wider than the rim, an aero disaster if you are riding at speed on mid-depth or deeper clincher rims. Steve

        • Thank you, Steve, that’s really interesting

          It indeed wider when I mounted those 25, it fatten up to 27-28 when inflated

          In other word, Tubular is not the same as Clincher, lesson learned

          I should try 23 sometimes later!

  • Hi Steve,
    For the 2016 Zipp 303 Firecrest wheels, would you recommend Conti 4000S in 23C or 25C size? I am inclined to go with the 25. However I notice that the dimensions of this tyre in your table above for the 23C size are actually close to 25mm, whereas the 25C is measured at 27mm. I am a fairly heavy 80kg rider, and while I can accelerate well, sprinting is not so important to me at the moment. So, not sure whether to go by the label or by actual measurement in this instance.
    All the best

    • Zipp recommend 23mm at the front to maximise the aero benefit and 25mm at the rear. I’ve used this and find it works well with Continental gp4000s2.

      PS 63kg front 85psi rear 90 psi.

      • Thanks. That might be a good idea actually, as most of the comfort (or lack thereof) I imagine comes from the back wheel anyway.

  • Steve–excellent article (as are your others). Particularly like your summary at the end of the pros/cons of the different combinations between rim width and tire size. Since it was not included in the summary, I wanted to ask about using 28c tires on rims that are 19c wide. I am currently using Boyd 44m carbon rims (19 internal width) with Conti GP 4000II 25c. They seem to work well, but I often ride on rough rural roads and wonder if moving up to 28c would help improve safety/handling and comfort without sacrificing too much speed from the negative effects on aero/weight. Thanks!

    • Brian, Would try reducing the pressure first. 28C on those wheels will improve your comfort as you’ll run them at a lower pressure but will also reduce your aero performance and won’t improve your handling. Steve

  • Caner, hard to answer that without knowing what you prioritize between speed, comfort and handling and with a better sense of your riding profile. I’d suggest you review the section of the post above that looks at those trade-offs and choose based on where you come out on them. Steve

  • I was convinced I had to go to 28mm. tyres on my standard Bontrager SSR rims. Thanks for clarifying that my 23 cm tyres are fine.

  • Hi Steve,
    Great article. My question on tyre / rim combination is obviously not about speed, but will it be safe? Conti Gatorskins 622-32 on 23C WTB rims. The Continental literature follows the ETRTO chart, and implies that nothing less than 37mm should be fitted on 23C rims. Is this overly cautious? I am 72kg.
    Thanks in advance for any advice you can give, and apologies if talking about a 32mm tyre makes you feel nauseous!

    • Robin, There’s an angel sitting on one shoulder telling me to answer you and a devil lawyer sitting on the other telling me to shut up! The angel says 32C road tires will be fine on a 23C road wheels but doesn’t know anything about mountain bike wheels and tires. The lawyer is pulling at my ear and suggesting you consult whoever sold you the tires. Steve

      • Quick response! I’m leaning towards the angel…. The Gatorskins are actually a high mileage road slick (with siped shoulders similar to the GP 4000S II) and the rims lean towards XC / Cross if that would influence your advice.

  • Steve,

    I am pretty sure I am beating a dead horse here but I have a question with regards to 23mm tires not being safe on Belgium + Rims. You stated above the challenge of different tires sizes, one brand measuring differently than another. I suppose you have to draw a line somewhere but it is confusing when a Vittoria Pave 25mm ( I realize they do not make this anymore) measures on rim the same as a Conti GP4000 23mm. And for that matter a Conti GP4000 23mm is only (inflated on rim) 1.4mm smaller. Does this little of a difference make one safe and another not? As I write this I feel like it is a dumb question, however I hope you see the dilemma as I could have bought a pair of Vittoria Pave 25mm and felt safe or bought the Conti’s and felt in danger per the article so curious about your thoughts here. Thank you –

    • Zach, No, that horse is still pretty much alive and running in every direction. Was trying to be a wrangler with this post but the hype machine tends to fight common sense by saying wider tires cures all without regard to rim width or rider purpose. While I can’t tell you what is “safe” – that’s up to how you set up your tires, wheels, bike, etc. and how you ride – either width tire works on that rim. HED says “25mm Plus clincher rim MIN/MAX tire width: 23 – 58mm” for the Belgium rim. They also note “Our wide rims increase clincher tire volume, causing actual inflated sizes to be larger-than-advertised on the tire. Inflated sizes will be 1-2mm wider on our 23mm C2 rims, and 2-4mm wider on 25mm Plus rims.”

      It’s more a function of how you want the wheels to perform – speed, comfort, handling – that determines which tires and width you choose for your wheels. The Belgium isn’t an aero rim so even if you went skinny (and the Conti 23C tires are as wide as many 25C tires), it’s not going to make you faster because of your tire choice. Go wider for comfort, but not so wide that you’ll be rolling the rubber up on itself if you do hard cornering. I think either tire would work well. Steve

  • Hi Steve – great article. I have a problem that arose from my desire to go wider. I have 15c tires and had 25c tires on them. I changed the tires to 28c (Conti 4000s ii) and now the front tire rubs against the fork. If I take the opportunity to upgrade tires to 19c tires, will the height of the tires be reduced? 19c is the widest recommended by Conti. Thank you!

    • I meant 15c wheels to 19c wheels

      • Whiz With, my guess is that your fork isn’t wide enough for 28C tires. You need 3-5mm between the fork and either side of the tires to prevent rubbing. Steve

  • I’ve been cycling for fifty years and ice skating for nearly as long [a neuropathy has taken me off my skates]. I have two types of skates; hockeys and speed skates. The blades of the speed skates are significantly thinner that those of the hockeys, 2 mm vs. 3 mm. The blades of the speed skates are long and ground flat with a contact patch of more than a foot. The hockeys have a hollow grind which obviates the center and are rocked with a contact patch of about 4 inches. Needless to say, the speed skates are much faster with no sacrifice of comfort despite a less supportive boot. I may be talking apples and oranges here, but I am unconvinced that a wider tire will improve my cycling with respect to effort or comfort. Former Olympic champion speed skater Eric Heiden moved into bicycle racing following his skating successes. It would be fun to know what size tire he runs. I do know that tires can be too thin. Many years ago I tired 700 X 20 tires which introduced control problems in strong crosswinds. I am quite happy with 700 x 23 tires and 3 cross spokes. Were I saddled with radially spoked wheels, I might find wider tires to be more comfortable.

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