Quote:
Originally Posted by Nevin
I've actually replaced a lot of low-profile tires because people wear them out prematurely because of UNDER-inflation. If you're not sure what to run in your tires, you can never go wrong with what is written ON the tire. Why else would they put it there? 51 is a bit high for MOST cars though, unless your car is heavy. With a 51psi tire, you'd want to keep at least 40 in it, in my opinion.
I'm doing a saab 9-3 tomorrow actually that has 225/45-17's on it, and they wore out because he didn't keep enough air in them.
Guess he thought 32psi was enough in a 44psi tire...
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I always treated the listed pressure on the tire as the maximum cold pressure for ANY fitment. That is not really a specific recommendation for any specific car.
I've always heard that proper inflation pressure depends on weight and weight distribution, as well as torque application. FWD vs RWD, or a predominantly front heavy car, or a heavy car compared to a light weight car...
There is no way in the world I would put 40PSI in my Miata's Toyo 215-45-16 T1-Rs... The stock recommendation is 28psi front and rear due to even weight distribution (with passenger/driver) and rear torque application. I usually keep it between 30 and 32, depending on how I watch the tires wearing, especially when I rotate them.
My Legacy similarly recommends 34-32 front rear, IIRC, but I usually go a few pounds above that, due to the low profile of the 225-40-18 General Exclaims... but the suspension is harsh enough, without pushing tire pressure above 40psi. 36-37 front, ~35 rear seems to handle, and wear well. Over-inflation will wear the center of the tire tread faster. Under inflation will wear both shoulders faster, if the alignment isn't causing other wear patterns or cupping.
Max inflation is not necessarily the same as appropriate inflation for a specific application. My Legacy certainly doesn't weigh as much as a G8 GT wearing the same tires, but weighing at least 600 more pounds. (and having to accelerate and decelerate that weight.)