Quote:
Originally Posted by Tahoe_Hybrid
Don't do it buy a tire that is rated higher you can buy passenger tires rated to 51PSI …...
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You are mistaken if you think that because a tire has a higher max pressure, it is somehow better. That's sometimes true, but not always, and in particular, for passenger car tires, it's mostly not true.
Why do I think that? Because tires are tested at the rating point - at the max load and its corresponding pressure (with a couple of exceptions.)
For Standard Load passenger car tires, that pressure is 35 psi, except for tires done completely in metric units where it is 36 psi (2.5 bar, 250 kPa) For Extra Load Passenger car tires, the pressure that corresponds to the max load is 41 psi (2.8 bar. 280 kPa)
So one would be correct to say that an Extra Load Passenger car tire is stronger than a Standard Load Passenger car tire - but that's because an XL is rated at a higher load.
Further, a LR E LT tire (rated at 80 psi), would be stronger than a Load Range C (50 psi), but, again, that's because the max load is higher.
But a Standard Load passenger car tire can only be labeled with a max pressure of 3 pressures - 35 psi (36 for metric), 44, and 51 psi.
And a little wrinkle in this: The speed rating test for H rated tires requires a pressure of 44 psi and for V and higher speed ratings, its 51 psi - So an H rated tire will either be labeled with a max pressure of 44 psi or 51 psi, but a V or higher rated tires can only have 51 psi max pressure.
The pressure for t and lower speed rated tires is 35 psi (even for the speed rating test), so a T and lower speed rated SL tire will be labeled with a max pressure of 35, 44 or 51 psi. That choice is arbitrary.
So why are the static burst pressures for passenger car tires over 100 psi? Because the structure of a tire is all about fatigue resistance - and to get it, the strength of a plies and belts has to be multiple times what is needed for the rated pressure. The principle is described here:
https://en.wikipedia.org/wiki/Fatigue_(material)
Hope this helps clear things up.