Quote:
Originally Posted by CapriRacer
I'm going to start in a completely different place.
Please note, I am only going to talk about the US based tire standardization organization - The Tire and Rim
Association (TRA). I am also only going to talk about Standard Load Passenger Car tires. I am not going to
talk about metric based tire systems or Extra Load (XL) tires. Those are done similarly, but talking about them
just complicates things
TRA sets the max pressure. They indicate that only 35 psi, 44 psi, and 51 psi are acceptable max tire pressures
for Standard Load Passenger Car (SL PC) tires.
If you look at the load tables, you'll notice that for SL PC tires, the load maxes out at 35 psi. Please note that it
doesn't matter if the tire says 44 psi max or 51 psi max on the sidewall. The load table is the same.
From an engineering perspective, tires are all about fatigue - and one of the principles of Fatigue is that if you
make something stronger, it takes more cycles before it fails. So plies are made considerably stronger than 35 psi
requires - about 4 or 5 times as strong.
That means a 35 psi rated tire should burst at about 140 to 175 psi - and that's about where that happens.
And remembering that tires marked 44 psi max or 51 psi max are built like 35 psi tires, you now have a picture of
the relationship between max pressure and burst pressure.
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I'm starting to believe that a 44 or 51psi max on a tire sidewall is marketing, and not a valid basis for determining vehicle specific tire pressure. All those two values do is tempt the, let's just say 'less knowledgeable', into inflating their tires to an even more ridiculously high pressure! So just assume standard load tables, 35psi, for passenger applicatations.
So burst is safely 3-4x any maximum cold pressure listed on a tire's sidewall.
I guess for tractor trailer and bus tires, oft pressurized to 90-105psi, have even a higher maximum pressure stamped on them, and an even higher burst pressure: 300psi and up...