Originally Posted by
cplager
Sorry, that's not correct. If you and your bike weigh 200 lbs and you have your tires inflated to 100 PSI, then you wlll have a total patch size touching the road of 2 inches. Regardless of whether or not you have 23mm or 35 mm tires.*
Wider tires wear longer for two reasons:
1) for a given pressure, they deform less. This is why wider tires have lower rolling resistance.
2) Consider the angle the contact patch makes with the wheel. It is a small angle in all cases, but for a narrow tire, you have a narrow but (relatively) bigger angle where as on the wide tire, you have a wide, but smaller angle.
Cheers,
Charles
* You might notice that as your tire pressure goes to 0, your contact patch does not become infinitely large. So this formula only works when the tire is inflated "reasonably."
Ok, I understand this. However I've read reports to support what your saying but then I read others that refuted it. Problem is with this lower rolling resistance thing is if a 32 has lower rolling resistance than a 20 then why not just use 48 or some such number assuming the tire weights were the same to take the rotational weight out of the calculation. Of course aerodynamics plays a role to some degree but at lower speed of say 15mph that won't play much into that if at all.
I actually just did this today due to this post! When I hit the brakes hard enough to lock up the rear tire the rubber left behind on a 23 is about pencil thin, whereas on my wider touring tire, a 32, it's about a pencil and a half wide. I inflated my tires according to this calculator:
http://www.dorkypantsr.us/bike-tire-...alculator.html So I did not put 100psi in both front and rear and on both bikes, I put in my weight at 160 pounds plus 21 for the road bike and 160 pounds plus 26 pounds for the touring bike.