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rate of tire air leak?(4 posts)

rate of tire air leak?kenyee
Sep 9, 2003 1:25 PM
Something that has always puzzled me is why bike tires need to be topped off each time you take a ride? They seem to lose roughly 15psi per week if you don't do this. Why do car tires no leak and bike tires leak?
re: rate of tire air leak?flyweight
Sep 9, 2003 3:02 PM
Simple: rubber is a naturally porous material. Why don't car tires leak? Also simple: they're substantially thicker than the inner tubes on a bike and so it takes the air that much longer to escape.
Several factorsKerry Irons
Sep 9, 2003 4:29 PM
The bike tire is MUCH thinner and at much higher pressure than a car tire, so you would expect a faster pressure loss rate. Drop your pressure to 2 bar and see how long it holds pressure. Also, the thickness of tubes varies, along with the quality of the valve seal and the tube material. All that said, if you're only losing 2 psi per day (15 psi per week) then why do you need to top off the pressure before each ride?
don't ride that oftenkenyee
Sep 9, 2003 5:39 PM
Sadly, only once every 1-2 weeks and much less soon w/ NE weather changing back to ski weather :-(