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Old 03-10-2011, 07:04 AM   #74 (permalink)
CapriRacer
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Quote:
Originally Posted by Frank Lee View Post
Yeah, I didn't feel like googling all night when the asker could do the same.
I did a quick check (Don't have time, now) and didn't find anything about passenger car tires, but assuming we can - and the value is 200 to 250 psi.....

http://en.wikipedia.org/wiki/Fatigue_(material)

That says that we need to consider the fatigue resistance. The sidewall of a tire goes through a cycle for every revolution. 50,000 miles is something on thee order of 30 million cycles.

S-N curves (Stress vs Number of cycles) are similar for most materials - and they show that after millions cycles the strength is actually 20% of the single event value (like a burst test would be).

So 20% of 200 to 250 psi is 40 to 50 psi. Isn't that about what is written on the sidewall? Perhaps that is what the tire manufacturers are referring to?
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