Tire Pressures for Max. Wear?

[Bob Z.]

Well I searched and searched with no luck - 2008 Boxster S with stock 18" PS2s: what would be the best tire pressures for long tire life?

I like to go fast but generally in a straight line, no track events, etc.

For what it's worth, the door jamb tag recommends 29/36. And I am aware of the rear negative camber.

Thanks in advance for your opinions!

[White987S]

I would say 29/36. Possibly 1 PSI more.

Tire wear should be the least of your concerns. You want the best grip and most fun!

[White987S]

Bob, I would also suggest:

1) Getting a very high quality tire pressure gauge

2) Check pressures very often and adjust the cold tire pressure accordingly

3) Get a tire depth gauge, and log your tire depths monthly or 1/4erly

For example, for about every 10 degree air temp change the PSI changes 1 PSI. So, in the morning you might leave on a drive the the air temp is 50. Later in the day it might be 70. So the tire will pick-up 2 PSI regardless.

I think this is more difficult to moderate early in the driving season (spring) and late in the driving season (fall) becuase you can easily see these large temp changes.

So, pick a PSI setting you like, and be very diligent to re-check (weekly), to get the maximum tire life.

Rear tires will wear about 2x's faster than your fronts. With proper care, I think you can get about 20K on the rears. But, for some owners they may only get 10K.

[Bob Z.]

Bob, I would also suggest:

1) Getting a very high quality tire pressure gauge

2) Check pressures very often and adjust the cold tire pressure accordingly

3) Get a tire depth gauge, and log your tire depths monthly or 1/4erly

For example, for about every 10 degree air temp change the PSI changes 1 PSI. So, in the morning you might leave on a drive the the air temp is 50. Later in the day it might be 70. So the tire will pick-up 2 PSI regardless.

I think this is more difficult to moderate early in the driving season (spring) and late in the driving season (fall) becuase you can easily see these large temp changes.

So, pick a PSI setting you like, and be very diligent to re-check (weekly), to get the maximum tire life.

Rear tires will wear about 2x's faster than your fronts. With proper care, I think you can get about 20K on the rears. But, for some owners they may only get 10K.

Thanks. After riding motorcycles for years I have a real good analog guage and check the pressures on all my vehicles on a regular basis (always when cold, out of the sun, etc.). I usually go with a pound over the recommendation in the door jamb so 30/37 should be fine and as you said, I'll have to try that for a while. Besides, the tires are new so they need to wear-in a bit as well.

[renzop]

Well, the longest tire wear will almost always be at the highest inflation pressure on the sidewall. However this will not always equate to safe handling or even tire wear.

The most most even tire wear is obtained with 0 camber and 0 toe. This will keep the tire pointed exactly forward and level. This will lead to the most even wear for a given pressure. However this will not always result in the best handling.

Everything is a compromise.

Regards,

Alan