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iTrader: (2)

I always assumed it was the same as what the OEM wheels/tire pressure is, but now I'm not so sure.

Any thoughts?

dc121

it should say the max pressure on the side of the tire. for instance, my Pirelli P7000 SS has a max pressure of 52psi. i usually inflate 'em to 47psi.

DDubb

I've got mine at 45psi.....225x40 R18

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iTrader: (2)

Guys, that's very very wrong. Look at the psi rating for your stock tires. It says 44 psi. The sticker inside the door says 32psi. PSI is based on the car, not the tire.

The problem is when you go to different sized tires. I've been at about 34-35 psi on my Dunlops. Not sure if that's right.

I did find a cool trick to figure it out. I may go do it later.

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There is a trick you can do to determine precisely how much pressure to keep in your tires for your particular vehicle. It will give you the best tradeoff possible between mileage, tire life, and comfort. Make sure you use an accurate tire guage so that once you learn this pressure you know it is correct.

With a cold vehicle and cold tires, air them up way over pressure. 40 psi would certainly be there. Take a chalk and mark a chalk line sideways across the tread of a front and rear tire. Drive your vehicle several yards (30-60 or so should do it). Now look at the chalk marks.

You should see the inside of the chalk marks worn off but the outsides should still be showing. In other words, the bowed out overinflated tire was wearing the middle of the tread and not touching the outside of the tread.

Release a couple of pounds of pressure from the tires and repeat the experiment. Continue until the complete chalk marks wear evenly. (You might want to lose another pound to make sure the entire tire is bearing down across the tread once the entire chalk mark disappears at the same time). You have now determined the tire pressure at which you are keeping the entire tread on the road.

Under this pressure you are wasting available fuel economy, generating excess heat, and prematurely wearing the tread. Over this pressure you will get better mileage at the cost of comfort and decreased tread life. Keeping at this pressure will wear the tire evenly and thus extend its life to its greatest extent and offer the best compromise possible between gas mileage, comfort, and safety (you'll have your whole tread on the road). The pressures may be a couple of pounds different between front and back for your particular vehicle application.

TL Daddy

Michelin recommends 3~4 psi over stock for lower sidewall 18"s - I have mine at 35 psi.

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iTrader: (2)

Thanks Jake.