OEM 18' Tire Pressure and Rear Camber Questions.............

[Johnny-5]

Ive been doing 35 Fronts and 43 Rears. Just changed my rear tires due to massive inner wear and they told me Im supposed to be at 36 Fronts and Rears?

Tire Sizes:

225/40-18 Fronts

265/35-18 Rears

Also is anyone else having massive inner tire wear? Do these cars have negative camber stock?

Thanks in advance.

[venturawildes]

I let my pressure get low and my backs wore out on the inside. I run 36 back, 32 front same size rims as you

[Johnny-5]

I let my pressure get low and my backs wore out on the inside. I run 36 back, 32 front same size rims as you

Thanks for the reply. This hole time I had my rears setup to high.

[balefire]

Ive been doing 35 Fronts and 43 Rears. Just changed my rear tires due to massive inner wear and they told me Im supposed to be at 36 Fronts and Rears?

Tire Sizes:

225/40-18 Fronts

265/35-18 Rears

Also is anyone else having massive inner tire wear? Do these cars have negative camber stock?

Thanks in advance.

I think your old tire pressures were fine and were close to Porsche recs.

Your alignment will affect the inner tire wear 100x more than your tire pressure will.

Yes, the stock porsche alignment has negative camber. You can dial it out, but understand the consequences in handling.

[san rensho]

Try to get as much negative canber out of the rear and get the toe to as close to zero as possible. It's hard to do both, but if you have to choose, get the toe to zero.

[Johnny-5]

Ive been doing 35 Fronts and 43 Rears. Just changed my rear tires due to massive inner wear and they told me Im supposed to be at 36 Fronts and Rears?

Tire Sizes:

225/40-18 Fronts

265/35-18 Rears

Also is anyone else having massive inner tire wear? Do these cars have negative camber stock?

Thanks in advance.

I think your old tire pressures were fine and were close to Porsche recs.

Your alignment will affect the inner tire wear 100x more than your tire pressure will.

Yes, the stock porsche alignment has negative camber. You can dial it out, but understand the consequences in handling.

So is what I had close to what Porsche recommends? Or is it 36? Im hearing 36 but I was told 44 so thats why I had it at 43? Can anyone else confirm factory specs for the 18' Wheels? Yea I figured that was the case and why it was having so much inner wear. I understand its for handling and has its consequences so Ill just have to make sure I flip them on occassions to prevent just the inside of the tires to wear only.

Try to get as much negative canber out of the rear and get the toe to as close to zero as possible. It's hard to do both, but if you have to choose, get the toe to zero.

Yea this car is due for an alignment so Ill have to take this in and have it checked out. Thanks for the tips.

[balefire]

36f/44r psi is porsche stock rec.

i flip my tires regularly due to the negative camber.

when in doubt, alignment is always a good idea.

[fpb111]

Look under your gas flap.

17" = 36 F & R

18" = 36 F & 44 R

2003 C2 Cab 18" rears, at ~12k miles = inner ~1/3 worn to 1st layer of cord outer 2/3 just about to the wear bars with factory alignment. Fronts ~25k inner at wear bars, outter just about to wear bars

This for the last two sets of tires. Michelins and Kumhos.

Edited January 21, 2013 by fpb111

[Johnny-5]

36f/44r psi is porsche stock rec.

i flip my tires regularly due to the negative camber.

when in doubt, alignment is always a good idea.

Yea I may have to start flipping them every few thousand miles from here on forward. I didnt really pay attention to the rears and didnt think they had that much negative camber on these cars stock. As for tire psi thats what I thought I knew I had the numbers right they kept stating to me that I was wrong and it was 36 front and rear. Yea Ill probably take it in this weekend. Just need to find a good place to take it to locally. Dont know if I trust some of these tire companies out here!

Look under your gas flap.

17" = 36 F & R

18" = 36 F & 44 R

2003 C2 Cab 18" rears, at ~12k miles = inner ~1/3 worn to 1st layer of cord outer 2/3 just about to the wear bars with factory alignment. Fronts ~25k inner at wear bars, outter just about to wear bars

This for the last two sets of tires. Michelins and Kumhos.

Gas Flap...interesting place to put it. Would help if I would pay more attention to things when filling up gas you think! lol Yea my fronts dont look to bad but I may have them do those next time around when I get the rears flipped. Thanks for the confirmation on the psi. I knew I had them right.

[Orient Express]

Try to get as much negative canber out of the rear and get the toe to as close to zero as possible. It's hard to do both, but if you have to choose, get the toe to zero.

This is it. Negative rear camber certainly helps handling, but is murder on the insides of the rear tires. Resetting the camber to 0 will double the rear tire life at the slight expense of handling. The rear feels a bit looser with 0 camber on the track, but for DD use, it is negligible. Zero rear camber can be the difference between getting 15K miles from a rear set of tires and getting 24K miles.

[logray]

I've got about -1.2 deg rear camber and I notice fairly even wear, that's interesting people would report more inside wear...

For pressure I run 31/36psi track, 35/42psi road. Achieved 30mpg with the road setup.

[san rensho]

Neg camber can cause inner tire wear, but usually its toe that causes the wear. Getting toe as cose to zero as possible will reduce inside wear.

[Johnny-5]

Try to get as much negative canber out of the rear and get the toe to as close to zero as possible. It's hard to do both, but if you have to choose, get the toe to zero.

This is it. Negative rear camber certainly helps handling, but is murder on the insides of the rear tires. Resetting the camber to 0 will double the rear tire life at the slight expense of handling. The rear feels a bit looser with 0 camber on the track, but for DD use, it is negligible. Zero rear camber can be the difference between getting 15K miles from a rear set of tires and getting 24K miles.

This car is driven about few times a week mainly by my girlfriend as I work mainly from home. Its not really going to see track not like the M3 Im currently building so if I can get as much as even tire wear as possible is my goal!

I've got about -1.2 deg rear camber and I notice fairly even wear, that's interesting people would report more inside wear...

For pressure I run 31/36psi track, 35/42psi road. Achieved 30mpg with the road setup.

If Im able to keep a little camber and have fairly even wear Ill be happy! Ill probably take it in later this week for an alignment and consider your deg and toe at 0. As for tire pressure I figured where I had it was good. I may consider using your psi for the road! :D

Neg camber can cause inner tire wear, but usually its toe that causes the wear. Getting toe as cose to zero as possible will reduce inside wear.

Thanks for post!

[balefire]

Neg camber can cause inner tire wear, but usually its toe that causes the wear. Getting toe as cose to zero as possible will reduce inside wear.

I'm not sure this is correct.

Toe will affect a greater portion / almost all of the tire whereas camber can cause inner tire wear.

Although you would like to reduce tire wear, remember reducing camber and making the toe close to zero as many have recommended will loosen the rear of the car which might make the car unstable in emergency situations for your girlfriend.

[RSrocket]

Ive been doing 35 Fronts and 43 Rears. Just changed my rear tires due to massive inner wear and they told me Im supposed to be at 36 Fronts and Rears?

Tire Sizes:

225/40-18 Fronts

265/35-18 Rears

Also is anyone else having massive inner tire wear? Do these cars have negative camber stock?

Thanks in advance.

I'm running the same size tires that you are on 8"F & 10"R wheels. I believe that the tire pressures of 36F/44R are for a full load and 32F/36R are for a 1/2 load. IIRC, Porsche issued a TSB about tire pressures.

I'm currently running 32F/36R PSI (weekend car) with stock alignment settings and so far find it a good compromise between ride quality and tire wear. I'm keeping a close "eye" on the rears for cupping and camber wear, so far so good. This wil all change soon since I'm in the process of replacing spings, shocks, & front LCA's.

Hope this helps :)

Ron

Edited January 27, 2013 by RSrocket

[Loren]

Here is what the TSB "actually" says...