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Tire Pressure

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Old Feb 26, 2006 | 02:33 AM
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Default Tire Pressure

When I had the car in earlier this week for the recall work, they service dept must have added air to the tires. Noticed it was taking the bumps in pretty brutal fashion, and riding pretty rough. Checked tire pressure today, and the rears were at 38, fronts at 34. This seemed pretty high to me, so tonight I decreased rears to 34 and fronts to 32. Made for a much nicer, less punishing ride.

Just wondering, what pressure everyone else is running?

For reference, I've got the Pilot Sports...
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Old Feb 26, 2006 | 02:38 AM
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37 F 44 R

On the OEM Contis
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Old Feb 26, 2006 | 03:14 AM
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The info is in the owner's manual and quick reference guide:

(looks like you're sporting some 19s based on your avatar photo)

18 inch wheels F 36 R 44
19 inch wheels F 33 R 39
19 inch wheels fully loaded F 36 R44
These specs are for both the base and S models

I check my pressures cold with a digital guage once a week and add or subtract air as neeeded

HTH
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Old Feb 26, 2006 | 09:11 AM
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IMO, 44 psi is too high on the rears. I had Pirelli P-Zeros on my car when I first got it with 6,450 on the clock. By the time I hit 8,500 the center portion of the rear tires were worn to the wear bar. However, the outside and inside parts of both rear tires had 5/32 left (new tread = 10/32). They wore out so fast that I wrote Pirelli USA and asked for some free replacement tires. They gave mt 50% off the replacement tires. I ran 39 - 40 psi on the replacement tires and got 12K out of them. I now have Bridgestone Potenza RE750 tires, both front and rear, and I am running 32 psi on the front and 40 psi on the rears. I may drop to 38 on the rears when the weather warms up.
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Old Feb 26, 2006 | 09:18 AM
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based on the door guide i have 34-35psi in the front and 40psi in the rear (19")
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Old Feb 26, 2006 | 10:02 AM
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What do you think is best for longer wearing life on contis 18" . I do not drive hard, I have now in 6 months 10k miles and both the front and rear seem fine. Although the front is looking better. I run 37-44
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Old Feb 26, 2006 | 10:05 AM
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I took lowest recommended values and highest on door sill and averaged them. (result is 36 and 44?, I wrote it on tire guage).

BTW, unless you have TPMS, check pressures with a guage often. IOW, you can be waaaaaay underinflated, and because of the low profile, it will be very hard to detect visually.
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Old Feb 26, 2006 | 10:09 AM
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Originally Posted by gota911
IMO, 44 psi is too high on the rears. I had Pirelli P-Zeros on my car when I first got it with 6,450 on the clock. By the time I hit 8,500 the center portion of the rear tires were worn to the wear bar.
Your tire history is hard to figure out, because you don't know how good the original owner was at watching tire pressures, but the most common cause of the center area wearing faster than the edges is underinflation , not overinflation.

I know that's sort of counter-intuitive, but wide, low-profile tires depend on adequate air pressure to hold their shape across the width of the tread surface. If the tire is under-inflated, centrifugal force deforms the center of the tread pattern outward, and greater wear results.
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Old Feb 26, 2006 | 10:28 AM
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Originally Posted by uzj100
I check my pressures cold with a digital guage once a week and add or subtract air as neeeded
HTH
How could you ever need to subtract air (provided you filed them with the right amount to begin with)?
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Old Feb 26, 2006 | 11:22 AM
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36f 44r tire wear is even across...
I measure them with a depth gauge.

Also remember that the inflation pressures are to be done at the
nominal temperature of 68° cold.
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Old Feb 26, 2006 | 11:22 AM
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Originally Posted by wross996tt
How could you ever need to subtract air (provided you filed them with the right amount to begin with)?

I imagine if it gets very hot out you would have to adjust tire pressure downwards but I've never had to do this myself.

Also in response to gota911's observation: I am using the door tire pressure recommendations. I have a base 911 with 18" Contis and have 50% tread on the rears after 11 K miles.
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Old Feb 26, 2006 | 12:26 PM
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So 36F 44R is a good pressure for 19s? You guys got me worried.
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Old Feb 26, 2006 | 01:49 PM
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bear in mind the psi differential for fully loaded and not...36/44 appears to be for a 2 stick figure family and their baggage....
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Old Feb 26, 2006 | 04:08 PM
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Originally Posted by caf
Your tire history is hard to figure out, because you don't know how good the original owner was at watching tire pressures, but the most common cause of the center area wearing faster than the edges is underinflation , not overinflation.

I know that's sort of counter-intuitive, but wide, low-profile tires depend on adequate air pressure to hold their shape across the width of the tread surface. If the tire is under-inflated, centrifugal force deforms the center of the tread pattern outward, and greater wear results.
It's strange you say that because about a month ago, when I was having a faulty seat heater switch replaced at the dealer, the service advisor mentioned that the rear tires (P-Zeros) were almost to the wear bars and would need to be replaced soon. I mentioned I had already order the replacement tires. He added something to the effert, "I did notice you have a nice even wear pattern across the tires. They are evenly worn on the outside and inside edges."
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Old Feb 26, 2006 | 04:11 PM
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gota911, you've got 18's and these guys are running 19's so it's a bit different. My 18's are usually at 33front/39rear but the 19's are always 36/44 because of the reduced sidewall.
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