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.


  • Hi Steve, Great job! Your articles on wheels/tyres are precise, nice to read and have a touch of personal opinion, which I very much value.
    I am planning to get a pair of carbon wheels for my bike. I am considering between a pair of 49mm depth with 17mm width versus 45 mm depth with 21mm width. I’m 170cm (72KG) and don’t race, 150-200km/week, averting 30-32 km/k on 100k with 1500 ascent. I do mixture of climbing and flats (50/50). I’m slightly concerned about side winds but my priority is handling, speed then comfort. I would be interested on your views. Many thanks. Rui

    • Rui, The depth and width specs alone don’t tell you much about how wheels will perform in different conditions. I’d suggest you take a look at my post on how to choose the best wheelset for your own riding profile here and my review of carbon clinchers here. Steve

  • Hi Steve,

    The zonda c17 has box rim profile (as you stated in your review) and shallow depth. Does this mean I should go with 25c instead of 23c tire (I’d buy conti gp4000s II) for more comfort? As you stated:

    “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.”


  • Hi Steve I’ve just purchased some conti 4000 s2 in 28c, I must admit I made an error when purchasing these and didn’t realise the size, I have a pair of Duraace c24, are these rims too narrow for the tires ? Thanks

    • Tony, you’d be better off with 23C tires on those wheels. Steve

      • Thanks for that Steve, I’ve spoken to shimano and to boardman bikes and although they say the larger tires would be ok I think I’ll follow your lead and stick to the 23c I’m running those at present and haven’t had any problem, so again thanks for the advice

  • You say “Easton’s EC90 Aero 55, they recommend an even larger tire-rim width difference.” which leaves me wondering what the difference is that they recommend. Alternatively, what tire width is recommended for those rims?

    • Dannyjeff, The leading wheelmakers work to a design guideline established by Zipp and borne out by wind tunnel testing that says the measured tire width should be no more than 95% of the wheel width. The Easton chart shows that the narrower the tire, the less drag. I probably went too far in saying that Easton recommends the 21mm tires at the top of the chart, but they are certainly suggesting that if you want to go faster in a time trial, go as narrow as possible. As I say elsewhere in the post, you have to set your priorities for speed, comfort, handling and make your tire choice based on the tradeoffs that come with those priorities. Personally, unless I was doing a time trial, I’d put a 25C Zipp Tangente Speed Road Tubeless 25C tubeless tire on it that would still be within the 95%, has low rolling resistance, and good handling. If you haven’t seen them, also check out my Know’s Notes posts from Sept 7 and 14 which get into tire width and pressure for different size rims and my review of tubeless tires. You can find these on the home page or by using the search bar. Steve

  • Nice to read this, it seems very reasonable! It’s amazing how much seemingly contradictory information there is online regarding tire width versus speed, usually presented with an arrogant tone. I have a few questions: 1) Why do the people talking about using bigger tires and rims often ignore the weight they add? Accelerating your bike is something you do constantly (look down at your Garmin as you ride), and every gram inhibits acceleration. No one comes close to holding an actual constant speed, even on flat smooth roads. Weight around the wheel’s perimeter is something you can really feel, and the “lab” numbers regarding the effect of rotating weight at the wheel’s perimeter seem to underestimate real-life experience. 2) What does the unit “C” mean? Aren’t we actually talking about mm (millimeters)? 3) Did the aerodynamic tests mentioned in this piece involve rotating wheels with a rider pedaling the bike? Tests showing the drag of a bike or component standing still are only useful for creating marketing hype. I believe that tests done with a pedaling rider show almost all of the drag coming from the rider and the air disturbance created by the spokes, making things like tire profile and frame shape virtually insignificant.

    • Cuomobike, As you note, there are a lot of different views on this topic. I don’t want to reopen a can of worms on this but my view on your questions are as follows:
      1) Acceleration is just one thing people care about. People typically go to wider tires for improved comfort and better handling and care less about speed or acceleration.
      2) I believe the C designation, as in 25C, comes from the standards body ETRTO. It is intended to reference tire and inside rim width in mm. While it’s still pretty close for rims (i.e., a 17C rim will measure pretty close to 17mm wide between the bead hooks), it is typically not the tire’s actual width once installed and inflated on the rim. Further, the width of tires designated with the same C size, like 25C, once installed and inflated will vary greatly depending on what size rim its on and the brand and model. I wrote more about this and provided a chart of different size tires from different brands on different brand and size rims here.
      3) Tests of the aero performance of wheels use all sorts of protocols. Their aim is to show the difference between wheels which is, as you say, a small percentage (<10%) of the overall drag for a bike rider. Whether it is is insignificant or not depends on what type of riding you are doing. Aero considerations of any type don't matter if you are a recreational rider tooling around at 15mph on a country lane. Every aero consideration matters from your helmet down to your shoes for the time trialist competing at high amateur and professional levels. Between those two points, it matters more or less depending on who the rider is and what they are doing on their bike. And for that reason, you have tests and gear made to do well on those tests. Steve

  • Hi Steve, Thanks for the quick and thoughtful reply. Yes, I definitely agree bigger tires (and rims) are all about more comfort and better handling, and not so much about speed. My point has more to do with the effect of adding weight around the outer edge of the wheel, which is sometimes ignored during the latest hype cycle. Steve

  • 20mm on 17C rim? Should be still safe, or?

  • HI Steve, I am a 220 lb rider on a 2009 Torelli Toccata Carbon road bike. I have recently bought some 25 mm carbon wheels mad in China (no name). I am unable to ride 25 mm tires on this frame as there is not enough clearance. Is it safe for me to be riding on these 23 mm tires on my new 25 mm rims, or should I switch back to my old set up. Thank you.

    • Paul, Hard to know from what’s in your email. You want about 5mm of clearance on either side of the rim or tire to your forks/stays. Tire size isn’t standard. They will measure up differently depending on the tire brand and model on different rims based on the rim internal and external dimensions. And putting your weight on a no-name carbon wheelset is a risk in and of itself independent on everything else. Steve

  • Is it safe or recommended to put a 23c tire on a carbon wheel that is 25mm wide?

  • OK thank you Steve.

  • Great article. I am looking to buy or build a set of wheels for the hill climb season the events near me will generally be short steep hills of 1.5-4 minutes averaging over 10%. Would you recommend wide rims and tyres for the slight rolling improvement of narrower rims and tyres that should come in a couple of hundred grams lighter. They will also be used for general riding so i will avoid tubs. Extra information i weigh about 62kg and will be aiming to hold over 650 watts for the shorter events speed will be between 10 and 15mph and i have about £1500 to spend if you have any recommendations.

    • Tom, The rolling resistance improvement for say a size wider rim and tire would be negligible compared to the notable benefit of saving a couple hundred grams. Check out my review of climbing wheels here for my recommendations. Steve

  • Hi Steve, great article and very informative! What will make more of a difference: upgrading to carbon 15c rims or aluminium 19c rims? I’m a 90kg rider and I want to run 33-40mm tyres.

  • I have a Bella Litespeed with a 650c Velomax Circuit wheel. I can’t find the inner width on the 650 but the 700c Velomax Circuit has an inner width of 14. I currently run 23c tires but would love a larger tire for comfort. Could I run a 25 or even a 28 on my 650c Velomax circuit?

  • I want to run 28 mil tires which is the best wheels, item around £1500 max my theory is We’ll should be roughly 29 mil wide On carbun. Wheels. and that’s in depth 45 mm max. Fo me what out there

  • Hi Steve,

    I’ve got 25 year old Mavic SUP 622- 13 700 rims, what the widest tire you’d recommend?


    • Rick, The ETRTO chart says you can go up to a 25C tire but I would think the handling wouldn’t be very good. A 20C tire would be ideal but hard to find. Probably a 23C would be a good solution from a fit, availability and price standpoint. Steve

    • Hi Steve,

      I found some 20c conti 4000 tires for my Mavic sup 622 – 13 700 rims for a great deal, under $50! Why would you prefer these, as stated above, over 23c. Thanks again!

      • Rick, 20C Conti 4Ks likely to handle better than 23C Contis at the lower pressure you’ll run them at for the improved comfort you want. If you run them at normal pressure for your weight, you could go with the 23C Contis. Steve

        • Hi Steve, Got the 20c and they’re great! With my old rims, they’re better than 23’s, noticeably. The handling improved more than anything, and they’re surprisingly comfortable also.
          Thanks for the great advice, and for the work you do

  • Hello there, great article. Q: what about tire height? I mean, if you fit a 25mm tire to a 15C rim, or if you’d fit a 28mm tyre to the same rim, what height does it give? Equally, my mind is set on a 28mm tirefor a 15C rim, suppposedly this will fit and be rigth. Howver, the bike was bought with and set up for 23C…. I am curious if there is a formula or a rule of thumb to establish tire height… as I need to find out clearance with the inside of the fork.

    • Si, for all the performance reasons I mentioned, I wouldn’t put a 28C tire on a 15C rim. If it makes you feel better, most 25C tires will measure 27mm +/- a mm on a 15C rim. Depending on your frame and brakes, at 28C tire (which will measure closer to 30mm +/-) also might not fit. Height is usually less of an issue than width. No rule of thumb as depending on manufacturer, 23C or 25C or 28C tires will measure differently in both width and height than others of the same “C” designation. Steve

  • Hi Steve, I’ve seen elsewhere that some of the combinations you listed are not recommended. More specifically, an ETRTO guidelines chart published by Mavic shows that 25mm tires are not approved for 19c wheels.
    Here’s the link:
    Wondering if you could clear this up for us?

    • Brandon, Frankly, the ETRTO bike standards are badly out of date and most don’t follow them. They are working on updating their guidelines but can’t seem to get everyone on the same page. Even Mavic which was one of the key sponsors/funders of the bike tire committee makes 19C wheels that they put their own 25C tires on. See the rim and tires spec section of their Cosmic Pro Carbon SL UST wheelset here.

  • Hi Steve,
    I just got Hunt wheelset with 22mm outer and 17mm inner width. I installed a Conti 4k 25s but the rear wheels is brushing with the brake bridge. I guess the tire height (depth) is too much or the tire slot for the bead where it sits are abit on the edge. Even if I reduce the tire pressure it still brushing. (frame is an orro pyro disk 2019)

    So question, which tire model do you think has the least depth on it for 23 and 25mms? For clinchers and tubeless? Also, does tubeless tires, in general, get less depth since it doesnt have a tube?

    Hard to find these info on the internet because all the discussions are centered on the width.

    Thank you in advance.

  • That is the kind of total picture study I can benefit from! We cyclists
    tend to be trendy folks, and sometimes the herd goes a direction that
    they think is beneficial with not all factors considered. So this was the
    most informative I have found after looking over articles the past few
    years. Thanks!

  • Hi, Great article, but still confused on my options. I have an 1979 Motobecane that I have turned into a single speed for just riding around the park with the kids. The tires are shot and not sure whether to replace just the tire or buy a new wheelset. The only markings i can read are on the tire and they read 700x20c, what would the best option be for a tire replacement for durability? if bought a new wheelset, what are my size options? Appreciate any input.

    • Kris, 700 is the tire diameter, which fits a standard 700c bicycle wheel. 20c is the tire width, which is quite narrow by today’s standards but probably just right for the wheel’s width which I’m guessing is 13c or 15c considering the age. You could go with a 23c tire, about as narrow as they make them in everyday tires now in something like a Continental Gatorskin (see here), a very durable tire. Steve

  • Steve, Great article, but I am a little confused about the dimensions Shimano has provided me and what tire makes the most sense. I am using the Shimano WH-RX010 rims.
    Depth = 24. Width = 23. Right now I am running 700×23 tires. But I am in the clydesdale division and I am thinking of moving to a 28 tire.
    Here is the link for my wheel:

    Does running a 28 on this wheel make sense, or am I crazy?

    • Colin, The 23mm width is the outside with. That likely means it has a 17mm inside width. I wouldn’t go with anything wider than 25mm. For more comfort, you could try dropping the pressure 5psi from where you normally inflate it to or get a wider, tubeless wheelset. Steve

  • Hi Steve. I have a pair of gen 1 Enve 3.4. They are 19C front with 26mm rim and 16C rear with 24mm rim. Would you recommend 23mm or 25 tire?

    • Linsen, Depends what you prioritize and how fast you ride. If you aren’t going at aero speeds (at least 18mph/29kph), putting a slightly wider tire on the wheels won’t affect your aero/speed performance. I also don’t believe the first gen 3.4 were that deep so limited aero benefit even if you are going fast. I’m surprised to read the rear is a 16C. Don’t remember differently but if that is truly the case, you might want to go 23C in the rear and 23 or 25C in the front. Steve

      • Hello Steve,

        I have 622×16 rims. They measure 22.2 outside width. 16.3 inside width. depth is 9.7 inside and 19.3 outside total. The bike came with 700-25c tires but I was going to put 700x23c tires on it. Would I be better with 25 or 23 tires?

  • I’m running an older Mavic CXP22 on an older Giant (2009) Defy Advanved and according to the specs the rims are 622×15 with a 21.2 outer width. I went from a 23c tire to a 28c and from about 110psi to 90psi. I’ve noticed a definite gain in comfort, but no noticeable drop in speed or handling and definitely no issues with filament or pinch flats. I know this is merely anecdotal and goes against the facts of the article, but it seems to work for me. Granted I’m not a competitive rider (except against myself) and I’m really doing it for health, recreation and Zen, but I do try to improve over average times and speeds for my usual riding routes and my 100 miles a week. Still a good article with lots to learn. Thanks. Jim

    • Jim, Your Mavic wheelset is too shallow for there to be any aero gain or loss from changing tire width. Likewise, your pressure is high enough to minimize pinch flats and not affect handling. Depending on your weight, you may find 110 psi on a 23c tire or 90 psi on a 28c far higher than you need and slowing you down as the tire bounces more than it should and creates more fatigue as your body absorbs the energy. Steve

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