Tyre size

[ls28harry]

Harry, if you don't mind me being to personnel, what is your weight, I am 5'8" in height and about 11st 2 in weight

I'm bang on 9 1/2 st which is just over 60kg. Helps being only 5'7''.

[coolboarder]

The Vittoria tyres I'm running state a minimum pressure of 100psi. Are they just covering themselves do you think, in light of your comment about 'what you feel comfortable with' CB?
-
At my weight, I probably wouldn't consider running them at less than that in any case. But what you're saying seems perfectly rational and I'm wondering whether they are trying to avoid a rash of 'tyre failure' type claims.

Absolutely, Michelin used to state something similar printed on the sidewall but I notice the packaging now comes with more sensible ranges. I suspect they have to take into consideration the average rider who may not be sure of their weight or may have an optimistic guess at it and to allow for loss of pressure if that is not being checked with every ride, indeed even loss of pressure during a long ride. I have had pinch flats when I've had a lazy moment and not bothered to check pressure before going out and its probably dropped to below 80, never had one above that though but of course it depends on the size of the tyre. I'm assuming 23mm here, I run the 32mm tyres on my 'cross bike at 45psi and don't get problems but harder than that and they are very uncomfortable off-road. Clearly like with car tyres we should be doing this all the time but it is impractical do so.

[Greg Quinn]

I persist with 110psi in my tyres to avoid punctures. I'm around the same weight as CB. I suffer from pinch flats at lower pressures. It's a compromise because there's no doubt comfort is better with slightly lower pressure tyres.

[phil tregear 2]

dang! I just bought some 20mm michelins for my new summer bike. Guess Im going to have to up my average mph . 25 should be no sweat ( ahem!),. I have an old dawes frame with loads of clearance. May be I should buy some 40mm tyres for that???

[coolboarder]

I have an old dawes frame with loads of clearance. May be I should buy some 40mm tyres for that???

I'm sure that is very tongue in cheek phil but at some point the weight of the tyre going uphill, its resistance to turning due to overcoming centrifugal force, the friction due to increased contact patch and the fact a big fat tyre is likely to have a poorer quality carcase and thus be less supple will outweigh the improved rolling resistance, 40mm may thus be pushing it! I would suggest the trade off comes somewhere between 25 and 28mm.