Originally Posted by
surgeonstone
3 mm. Pretty small indeed.
Not even that when I had mis-matched rims. The "25" measured 26 on the rim, while the 28 was in practice 27 mm wide, so it was 1 mm.
Now that my rims are the same at least my 25's are both actually 25 mm wide, but I can't tell any difference between those and 28. Speed, weight, cushion, traction, literally I don't see a difference. So to me they're the same, whatever I feel like putting on at the time.