Since I bought a second hand mtb, I’ve noticed the wheels are two different brands, and the front tyre is a 2.1 tyre and the rear is 2.2. Doesn’t sound much but visually the rear seems a fair bit bigger.
If I put a 2.2 on the front would I lose much speed on my tarmac commute? Any benefit or loss in changing to both sizes all round or am I over thinking it and leave as is? Same applies for the less frequent times I spend off road
It depends more on that actual tyre itself, e.g is it fast rolling or a super grippy tyre. For general road riding you could get something that’s slick which would be faster but if speed isn’t a great concern then don’t worry about it. In all honesty if you’re just commuting then don’t worry about it.
I’ve always run 2.25’’ but last winter I changed to 2.1’'. Don’t know if it was the wider rims, going from 22,5mm to 25mm, but I can’t really tell the difference.
1 Like
You’re overthinking it. There’s a pretty small difference between 2.1 and 2.2. You could swap between two of the same tire but in different materials and have a greater difference in rolling resistance than swapping between a similar 2.1 and 2.2 tire.
The fastest option is just to put slicks on, but i don’t think that’s really necessary. I’ve done a bunch of tarmac rides on my XC tires, it works just fine.
1 Like
cool, I’ll most likely throw a set of wider tyres on when these are run down. If anything I’ll get extra training benefit from the resistance on my commutes 
What was your thought process behind switching from 22.5 to 25mm while running tires <2.4". I’m trying to understand the differences but came to the conclusion that this is mostly a preference rather than an actual benefit. I’ve come across a thread on the mtbr forum where someone pulled together all the inner rim widths recommendation for certain tire widths from different manufacturers. they made a chart with the averages of recommended min, opt and max tire sizes for a given inner width. the conclusion was that stans is on the narrower and enve on the wider end of the spectrum with their recommendations.
22.5 and 25mm inner rim width fall in the 1.9 to 2.35" ballpark so I’m wondering why people choose to ‘upgrade’ when they’re already in this range.
Actually it was like this.
I purchased a BMC Fourstroke 01 2017 with 22,5mm XR1501-wheels on it. I was so happy with the bike but needed one to keep me riding through winter so I got a BMC Teamelite 01 with 25mm XR1501’s which I crashed and the insurance let me keep the wheels so I replaced the 22.5 on my Fourstroke with the 25mm and then got a new Teamelite with 25mm wheels.
Meaning I had the exact same setup on both bikes. Now…
The biggest change I found was that I could lower air pressure with the wider rims and using the same tires. Other than that… Nothing remarkable.
hey, thanks for the reply!
lower pressure without tire squirm? I’m running 1.6bar (23psi) in the front and 1.8 (26psi) in the back on my xc ht. I have yet to try lower pressures but am concerned about rolling resistance on hardpack.
somewhat on topic: I had bontragers xr1 2.2" on 22.5 dt swiss xrc wheels and switched to a maxxis ardent 2.25" in the front and ikon 2.2" in the back and noticed that the maxxis seemed both less voluminous and narrower. as others have pointed out it comes down to the tire itself. will try 2.35" forekaster and 2.2" rekon in the back for the wintermonths and see how those compare to the bontis. my frame doesn’t clear bigger tires than 2.35" unfortunately.
1 Like
No tire squirm no. I ran Schwalbe Racing Ray front and Racing Ralph back at 1.35bar/1.40bar both 2.25’‘. I also ran Vittoria Barzo 2.1’’ front and back during the winter with pressures of 1.5/1.6bar. I weigh 69kg for reference.
I got my new bike last week and haven’t converted it to tubeless yet but that was delivered with Ardent Race front and Ikon back so I’ll try those out on the 25mm rims and see what air pressure I can get away with. Probably around 1.3-1.4bar there as well or even lower. They look “wider” or more voluminous than the Schwalbe-tires I had before.
i’d be interested in the actual (measured) tire width of those two tires on your 25mm XR1501 wheels and see if they are any wider than on my xrc 22.5 rims. so, if you’ve got nothing else to do this evening… 
@82/83kg i’m not willing to go as low as you are on those xc bikes
I’m sorry but I can’t help you with that because both bikes are sold. However I can measure the Maxxis-tyres once I get them tubeless. And I remember the Vittoria-tires being like 2mm narrower than the Schwalbe Rocket Rons on the 25mm rims.
1 Like