700c/32c or 700c/25c

[Cycling_Samurai]

I have 28s on my bike. Came with 25s. After reading about the difference between the two I opted for the larger. I would go 32 if my bike could take it. But 28s do just fine. I run Continental Gatorskins on mine for puncture protection. They are heavier than Marathons and there are plenty of faster tyres out there if you want speed. I'm an experienced beginner so I'll stick to my Gatorskins. Better for me when I'm 100 miles from home. Less chance of wasting time changing tyres.

 

[gom]

if rims are good for 32 I wouldn’t expect a 25 to be happy on them, you'll be sacrificing depth (rim-to-road distance) for width

Plenty of rims will cope with both - Conti have a nice online table listing the "sanctioned" combos. Worth checking.

And some won't?
In my single experience where I replaced a kaput 32 (which looked good on the rim) with a 25 (all I had spare), the ride was horrible and it looked ridiculous, more like a strip of tape than a tyre.
I suppose it depends ....

 

[Cycling_Samurai]

And some won't?
In my single experience where I replaced a kaput 32 (which looked good on the rim) with a 25 (all I had spare), the ride was horrible and it looked ridiculous, more like a strip of tape than a tyre.
I suppose it depends ....

Some people put 25c tubes in 28c tyres. Makes the tubes thinner and more easily punctured

 

[DCBassman]

I'm very much a whatever-is-on-there rider. My road bike wears 25s, which is the biggest that will fit. The town bike wears 28s, because that's what I had handy. The Trek rigid mtb, the least used, had had the tyre experimentation, and now wears either 38 or 50mm Schwalbe City Jets.

 

[nickyboy]

No. As @mjr says 32's will be comfier and will run smoother on typical crap UK road surfaces.
You'd do well if considering upgrading to swap the tyres to something like a Schwalbe Marathon Supreme.

If you check the rolling resistance stats Schwalbe Marathon Supreme comes in about 7W per tyre more than Continental GP5000. Of course there is some element of tradeoff with puncture resistance, but not huge

14W may not matter to the OP but it's rather a lot, probably 10% of total power lost in additional resistance. It's something to consider. For some cyclists puncture resistance is the key, for some it's low rolling resistance. I suspect for most it's a combination of the two.

 

[T4tomo]

I suspect, given its a trek bike, and 32mm tyres its likely to be a Domane and fitted with one iteration or another of Bontrager Hardcase lite tyres, which are pretty decent. I would stick with them as specced.

 

[NorthernSky]

i've only ever known 23c so can't comment.
if i ever get a new bike able to run 32c my a**e won't know itself

 

[Gunk]

Nope, one of my bikes has 23s, no clearance for anything else

Same here, but my Van Nicholas runs on GP5000 28c’s which are super comfortable

 

[DRM]

My Marin runs either 32 mm GP5000 road tyres, or Vittoria Terrano Dry in 33mm for gravel riding, both are very comfy, going to 25mm would be a backwards step and give a worse riding experience

 

[boydj]

I tried marathons on my commuter - they only lasted a couple of weeks before the wooden ride made me change them for Conti GP 4-Seasons which had a much better balance of puncture protection and rideability. If it was only the commute, I might have stuck with the marathons, but I liked to take the long way home at least once a week, which could be anywhere from 30 to 50 miles which would have been torture with the marathons.

I'm in the 'stick with what you've got' camp. The 32s will give a better ride and you could come down to 30 or 28 when they wear out.