Mr Tuffy’s legendary tire liners prevent puncture flats using their lightweight super-durable urethane liners. The new XL series is made for fat bike and fits tires up to 5. 2XL fits 2629 x 2.35-3.0. 3XL fits 2629 x 3.1-4.0. 4XL fits 2629 x 4.1-5.0