23mm or 25mm Tyres?

by Jonty79   April 21, 2010  

Hi All

I've been running my road bike for a year and need to replace the stock tyres that came with the bike. These are basic Bontrager 25mm tyres.

No interest in racing, but at the same time don't hang about! Just like nice long runs in the country and am entered in a few sportives this year.

I'm thinking about changing to 23mm tyres for less rolling resistance. Trouble is I'm not the lightest of riders at 15 stone, and the roads around me (like most places) are pot hole ridden!

Appreciate any views on whether 23 mm tyres are worth the sacriice in comfort and I guess bigger puncture risk for the better performance over 25mm tyres?

Have been thinking about Bontrager Race X lites?


11 user comments

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I run 23mm on my nice weather bike and 25mm on my winter trainer.

If you know the routes and know of very rough roads then go 25mm, otherwise 23mm and keep a lookout!

There are some who won't notice the difference between 25/23 mm.

I find cornering and wet weather riding can be fine on 23mm but use a good quality tread.

I'm trained with 25mm tyres with riders on 23mm no probs.

Zaskar's picture

posted by Zaskar [137 posts]
21st April 2010 - 15:17

1 Like

I run 25mm tyres on everything except my TT bike. but then, I'm a big lad. like you.

In terms of rolling resistance there's no engineering reason why a 25mm tyre should be inferior. in fact, it's much easier to argue the opposite. What 25mm tyres are, however, is heavier. That's what'll slow you down. Not all of them mind: you'll probably find 25mm rubber plenty lighter than the stock tyres you're replacing if you shop around. continental do quite a few in 24mm too.

Dave Atkinson's picture

posted by Dave Atkinson [7805 posts]
21st April 2010 - 15:38


I have just put some Race X Lite Hardcase 25s on my SCR and I'm impressed. They're much better than the standard 350g Hardcase tyres. The postal scales says they weigh 255g each, which isn't too shabby and about the same as the Rubino Pro 2s I have used and liked (there's a new 150tpi version of those out now).

23 v 25mm isn't worth worrying about - about 15g. A colleague picked up some Schwalbe Durano 23s from the LBS. They look at least as wide as my 25mm Bontragers and sizing does vary across brands. I have read an explanation how rolling resistance isn't related to tyre width but can't remember why. Am not sure you'd notice any difference in comfort but the larger tyre volume will be better, all else being equal (in which case why not go for 28 or 32mm?).

Simon E's picture

posted by Simon E [2338 posts]
21st April 2010 - 16:54


This is my understanding, which is probably flawed:

On a flat surface, rolling resistance is supposedly lower with a wider tyre inflated to the same pressure since the contact patch is shorter and wider. ie: The tyre isn't distorted as much.

But with a rougher surface rolling resistance is lower if the tyre pressure is lower, since (maybe) the tyre soaks up the bumps and energy isn't wasted moving the axle up and down relative to the ground.

So it isn't a simple answer. You might say "all things being equal, then...", but things usually aren't equal. I have a feeling that lot of riders who are pumping their tyres up to 110 psi are only achieving less grip and giving their teeth a good rattle.

I read that Juan Antonio Flecha rode his 28 mm tubulars at 75 psi at Paris-Roubaix.

two wheels good; four wheels bad

posted by cat1commuter [1425 posts]
21st April 2010 - 17:43


If memory serves, in Mike Burrows' book on bicycle design he says there is no point in pumping a tyre up beyond 100PSI that it gives no appreciable performance gain.

Tony Farrelly's picture

posted by Tony Farrelly [4201 posts]
21st April 2010 - 18:15


tony_farrelly wrote:
there is no point in pumping a tyre up beyond 100PSI that it gives no appreciable performance gain.

I have read that higher pressures causes greater tyre deflection over the surface irregularities. Plenty of these on the roads I ride, and it leads to increased rattles, bumps and rider discomfort Sad

I usually use about 70 psi, sometimes 80-90 psi for the club time trials in the summer. Michelin recommend a range of pressures based on tyre width and rider weight. See the PDF on this page:


Also http://www.schwalbe.co.uk/pdf/techinfo.pdf

Simon E's picture

posted by Simon E [2338 posts]
22nd April 2010 - 9:05

1 Like

Hi All

Thanks for the great advice - am probably going to stick with the 25 mm tyres and order a set of Race x lite hard case for the durability!

Thanks and enjoy the riding this weekend - great weather!

posted by Jonty79 [29 posts]
23rd April 2010 - 16:19

1 Like

Had two punctures in 100psi 25mm tyre (8 months apart).

Plenty of mileage but time for a change me thinks!
But will be opting for 23mm for summer.

why? Well I'm assuming less resistance but not much.
Might buy 25 or 28mm replacements for winter once I check the rim spec and spacing. Thinking

Dam just checked that 25's are the biggest I can squeeze on my rims.

Check rim size before choosing a tyre size folks!

Zaskar's picture

posted by Zaskar [137 posts]
30th April 2010 - 15:07


How narrow are your rims? Most "racing" rims are 14 - 15 mm inside width between flange beads, and in theory 28 mm tyres are the max. recommended width. In practice people run 35 mm cross tyres on them.

Frame and brake caliper clearance is more often an issue. Current Campagnolo brakes have worse clearance than SRAM or Shimano calipers.

two wheels good; four wheels bad

posted by cat1commuter [1425 posts]
30th April 2010 - 15:56


FWIW I have been using Bontrager Race Lites for years in both 25 and 23mm versions.

I can't really notice any difference between them, though I use 25 on my audax bike and 23 on my road bike - more as an article of faith than anything else.

Overall though I think they are the best value tires around, for puncture protection v price v performance.

posted by ChrisO [11 posts]
3rd May 2010 - 8:03


at a shade over 20st I use 23mm on my Ribble and have done without an issue for almost 4000 miles and my new Surosa has 25mm, the 25mm do feel a little better but I had a tank slapper on Friday in the wet, still dont know I i didnt lose it, I suspect that the type of tyres (23 are Armadilos and the 25's are Conti sport contacts) and not the size were the cause of the bambi syle sideways skid Big Grin

posted by shrinkinbggaz [117 posts]
3rd May 2010 - 14:30