Quote:
Originally Posted by PaleMelanesian
The car's recommended pressure is most definitely NOT right. My last set of tires, rated 44 psi, I ran them at 35, while the car called for 32. The wore out on the edges more than in the middle. That's above the recommended pressure, and it was still too low.
The question that remains is this: How much higher than this would be the best compromise between tread wear, traction, tire fatigue, and mileage?
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I cite this website ad-nauseum :
the wheel & tyre bible - Page 2
http://www.carbibles.com/tyre_bible_pg2.html
Quote:
The Max. Pressure -10% theory.
Every tyre has a maximum inflation pressure stamped on the side somewhere. This is the maximum pressure the tyre can safely achieve under load. It is not the pressure you should inflate them to.
Having said this, I've given up using the door pillar sticker as my starting point and instead use the max.pressure-10% theory. According to the wags on many internet forums you can get the best performance by inflating them to 10% less than their recommended maximum pressure (the tyres, not the wags - they already haves inflated egos). It's a vague rule of thumb, and given that every car is different in weight and handling, it's a bit of a sledgehammer approach. But from my experience it does seem to provide a better starting point for adjusting tyre pressures. So to go back to my Subaru Impreza example, the maximum pressure on my Yokohama tyres is 44psi. 10% of that is 4.4, so 44-4.4=39.6psi which is about where I ended up. On my Element, the maximum pressure is 40psi so the 10% rule started me out at 36psi. I added one more to see what happened and it got better. Going up to 38psi and it definitely went off the boil, so for my vehicle and my driving style, 37psi on the Element was the sweet spot.
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The emphasis is for performance. If you're cautious like me, it's a great place to start you tire PSI. I am now at max sidewall pressure (51 PSI) because I am comfortable with staying within the tire's design limits.
CarloSW2