But in the past year, the preferred tyre size for gravel racing has ballooned dramatically. Pros, especially, are now overwhelmingly choosing mountain bike cross-country racing tyres with widths ranging from 50 to 57mm.
In a nutshell, it’s because wide XC race tyres with lightweight casings have been tested to roll faster, compared to narrower gravel tyres. The rougher the gravel, the faster the XC tyres get, but even on smooth gravel, there’s no loss in speed compared to a narrower gravel tyre. Combine that with the improved puncture resistance of a wider tyre, and it’s easy to see why gravel riders are trying to squeeze the largest tyre possible into their race bikes.
The problem is that most gravel bikes on the market do not officially clear tyres that big. Well, officially at least. The tyre clearance listed by the manufacturer is often on the conservative end. This is done for various factors like allowing for enough mud clearance or to account for wheel flex or a slightly out-of-true wheel. They put some wiggle room into the stated maximum clearance to keep riders within safe operating parameters, and not constantly wearing away the paint or carbon of their gravel frames.
Dan Chabanov
Now, if you’re a gravel pro, the extra safety margin is ripe for filling with a larger tyre for the sake of performance. Paint and frame integrity be dammed.
I got up close and personal with pro racer Torbjørn Andre Røed’s Trek Checkmate at the Sea Otter Classic – the 2025 Lifetime Grand Prix kick-off race. It was obvious that he was ignoring the prescribed 45mm maximum tyre size by using a 2.1-inch Schwalbe Thunder Burt (54mm) up front, and a 2.0-inch Continental Terra Hardpack (50mm) on the back.
Torbjørn finished 11th at Sea Otter, so this tyre combo is clearly working well for him. But before you rush out to try and fit the widest possible tyres onto your gravel bike, please observe the following photos:
Dan Chabanov
Dan Chabanov
Dan Chabanov
This kind of paint and frame damage is only acceptable to professional riders who are not paying for their bikes. If you bought your own bike – basically, the rest of us non pros – it’s not worth damaging the frame and voiding the warranty to gain a performance advantage. Not to mention the added risk (however small it might be) of having the frame fail during a ride.
Pro racers make decisions motivated by performance, and sometimes those decisions contradict the manufacturer’s recommendations. Unless you’re getting your bikes for free, it’s best to listen to the people who designed the bike, not the ones racing it! And it’s worth remembering that just because a given tyre can spin in the frame or fork, if it’s over the stated maximum by more than a few millimetres, there will probably not be enough room in the frame to let that tyre spin freely under all circumstances, especially when riding off-road.