Those are two of the most popular questions we get asked – so we thought we would give a rundown of the most popular tyre sizes and types, along with their strengths and weaknesses.

 

Whichever tyre size suits your riding best we’ve got a bike to fit the bill, from road, to touring, gravel and everywhere in-between. 

 

We’ve focussed on these crossover bikes because that’s where the major trade-offs appear – hopefully everyone knows that the road isn’t the place for a 2.6inch mountain bike tyre!

 

Before we go any further, we need to add a note about tyre sizing! Different manufacturers will measure the width of their tyres in different ways. This means that many tyres will measure several millimetres more than their stated size. 

Best of all – this can also be impacted by the choice of rim that you mount the tyre on. 

With this in mind, whenever choosing your tyres you need to pay attention to whether they will fit in the frame – and we don’t mean if they will just go between the forks/stays. 

You need a good amount of clearance to ensure that when the frame, tyre and wheel all flex at the same time, that there’s enough room for the wheel to keep turning. 

Otherwise, your tyre is going to hit your frame and start wearing that material away, which is a bad thing.

That’s the safety notice done with – here’s what you can expect from the tyres you’ll find on the various Genesis bikes across the range…

 

700c x 23, 25, 28mm




Use: Road
Tread: Slick
Pressures: 60-100psi (check the sidewall of your tyres for manufacturer limits)
Featured on: Equilibrium, Equilibrium disc, Zero, Zero Disc, Volare, Volare Disc, Flyer

The reserve of pure road bikes, tyres measuring between 23mm and 28mm are predominantly completely slick and designed to be run at high pressures. 

 

While 23mm variants pumped up to 120psi are now rare, a 28mm road tyre can significantly improve the smoothness of your ride and increase your speed for the same effort.

On smooth and average tarmac, these are the fastest tyres you can use.


The 28mm variants especially, when run at lower pressures absorb imperfect road surfaces, can handle light cobblestones and can be sparingly ridden along dirt and compacted, fine gravel. 

But once off road their limits are exposed, with the wear-rate and risk of punctures increasing greatly, thanks to the lighter materials used.

If the gravel you’re riding along is loose, don’t expect much in the way of grip when climbing out of the saddle. And it’s probably best to avoid corners altogether. 

If you’re sticking to covering longer distances on predominantly well-maintained roads, read no further. 

If you value comfort and versatility above all-out speed, read on. 

700c x 35, 38mm




Use: Mixed terrain
Tread: Slick, file, semi-slick
Pressures: 40-80psi (check the sidewall of your tyres for manufacturer limits)
Featured on: Croix de Fer, Datum, Day One, Vapour Alloy, Fugio, Tour de Fer

The established generation of gravel bikes all feature clearances for wider tyres, meaning they can be used on a wider range of terrains. 

While these are not suitable for rock-strewn mountain bike trails, they certainly aren’t limited to the road either and that’s predominantly down to two things – grip and durability. 

There are a huge variety of tyre types available in this size range and their appearance dictates just how far off the beaten track you’ll be able to travel. 

A 35mm slick, or tyre featuring a fine, file tread is still limited when it comes to venturing off road. 


But it will double-down on those characteristics of the 28mm road tyre – greater comfort, better broken-road confidence, puncture resistance and grip. Basically, an ideal winter training/commuting tyre for when the roads are in an awful state, and one you can happily ride over dry dirt tracks in summer. 


 

Go up a size to 38mm and add some side knobs and you’re skewing the characteristics of the bike towards looser surfaces. 

Side knobs mean your tyres will grip when turning on gravel, in exchange for slower rolling slightly less cornering grip on tarmac.


Obviously, both of these tyre types will give up a little in speed to the 28mm road slick, but you may now find yourself riding off road more.

 

Finally, there are cyclo-cross tyres. Typically thinner and with knobs all over, they are designed for riding (and often racing) in the mud. 

 
650b – 47-50mm




Use: Off road
Tread: Semi slick, full knobbly
Pressures: 20-40psi
Featured on: Fugio

At this point we’re very much in the drop-bar, rigid mountain bike category.

 

The huge volume of these tyres will absorb rocks, roots and steps which means that almost every trail is a chance to ride. 

 

But all of that comes at a price. Slow rolling on tarmac - especially when running low pressures - and a significant weight penalty mean these are slanted firmly in the favour of dirt tracks. 

A perfect choice if your rides use a few bits of road to link an otherwise off-road ride. 


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