Quote:
Originally Posted by darcane
Cool video, thanks Metro.
I wonder what it's rated pressure is, probably 35psig for an older tire? If so, that's still about four and a half times it's rated pressure.
Typically in engineering, things are designed to a safety factor. Safety factor of 2.0:1 means that it was designed to twice the rated load. For the products we design where I work, because the failures could cause death, safety factors are 4:1, 6:1, or 10:1. I can see tires being in the same category, so I would expect a 4:1 or 6:1 safety factor. I'm impressed that the tire still has such a high burst pressure considering it's age.
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Don't forget about fatigue. In tires, that's the most important thing.
If you look at a typical S-N curve for rubber - and consider that 100,000 miles is about 6 million cycles - then the S-N curve says the failure stress is about 1/4 to 1/5 the static value. If you divide 220psi by 4 or 5, you get 55 and 44 psi. Isn't that interesting!