I recently (8 months ago) purchased a 2006 C2S. I know it was set up for occasional track use. I noticed the the tire wear is very uneven, especially in the rear. There appears to be a positive camber. The inside of the tires are wearing faster than the outside. The rears are also 305 as opposed tot he 295 OEM. is this uneven wear a result of the track setup, the wider tires or just due to the way the car is from the manufacturer? I would like to figure it out before I get new tires (295s)

Thanks

 

911's wear from the inside due to the way the car is. People forget a 911 is not a typical car. (Rear engine behind the rear axle) I defies logic and also normal tire wear!!

 

Actually, if the tires are wearing on the inside that reflects negative camber, not positive.

911's are always set up with a small amount of negative camber. They're
famous for wearing out the insides of the tires, especially in back. In street use, front tires will typically last twice as long as the rears.

A car set up for the track will almost certainly have even more negative camber in the suspension. While this is a good thing on the track, on the street it means the tires (and especially the rears) will be short-lived.

If you're not going to track the car, get it realigned (always a good idea anyway) when you buy new tires. It appears you'll want the minimum allowable negative camber, as opposed to a track setup which is probably close to the maximum possible negative camber.

Even with the changed settings, unless you drive very conservatively you're going to go through rear tires pretty quickly. I'm afraid that's part of the price of having a 911.

DMoore
'11 C2 GTS
'10 Panamera 4S

 

Thanks for all the insight

 

07 S....put 19k miles in 13 months....2 track days....never touched the tire pressure...tires still had life left. OEM Michelins. Did not see any unusual tire wear.

 

Just a thought..... If you put a positive camber on the tires would it help counter-act the engine weight. I will not track the car

 

The swing axles that existed years ago on Corvairs and Beetles would result in positive camber. Remember how easy it was to flip those cars, and the lawsuits that ensued? What was that guy's name? Oh yeah --- Ralph Nader.

You will NEVER want to see positive camber in a 911. LESS negative camber, sure, but it will never get to 0 - let along into a + camber. Positive camber will destroy the car's handling at a minimum, if not render it wholly unsafe.

Buy cheaper tires - drive more cautiously - just don't even think about positive camber!

DMoore
'11 C2 GTS
'10 Panamera 4S

 

I have -2 degrees camber in the rear on Michelin PSS. They currently have a little over 8000 miles on them and they still have plenty of tread. The inside edges are a bit more worn than the outer edges.

 

Drive more aggressively around corners and you'll notice a more even wear pattern. They'll wear faster but that's another issue ;-)

 

I'm down to 2 track events a year. But they do get pushed on those occasions.

 

What kind of wheels are you running? The Sport Design wheels I have (11.5 inches) came with 305's.

 

If the car is showing positive rear camber the alignment is woefully wrong.

What you are probably doing is mistaking negative camber for positive camber.

IOWs, negative camber has the rear wheels when viewed from straight behind the top of the wheels closer to each other than the bottoms.

Now it will look like the car is running on the inner edges of the rear tires.

Looks can be deceiving.

Remember you are looking at the car while it is stationary. What the car looks like, the orientation the wheels/tires take when the car is moving and the orientation they maintain as the car (constantly) changes direction while is something else.

The wear you are seeing is due to mis-alignment. Rear toe is wrong (at least).

Get the car properly aligned. Trouble is with the worn tires the outcome may not be that dramatic.

So you should next time you put on new rear tires (or replace all 4 tires) get the car *properly* aligned. Stock settings should be used as starting point.

Couple of things to prepare for an alignment: Be sure the gas tank is full. Remove all junk (dead weight) from the car. If a spare tire/tool kit came with the car be sure all are installed and properly secure.

With the car properly aligned and under reasonable usage the tires should wear evenly. I have managed nearly 23K miles on the rear tires of my 996 Turbo and tire wear was quite even.

If you get the car sideways some I can't say what tire wear will look like but it will still be better with a proper alignment than it would be otherwise.

 

+1
Adding negative rear camber for a track set up can also increase toe OUT of the rear wheels. Also, if the car is lowered at all without an alignment toe OUT is increased. I know from experience, this can vaporize the insides of rear tires! If you've already recognized rear tire wear, by the time you get them off, the insides will probably be close to the cords! It happens very quickly.

 

Soft compound, negative camber, toe in and majority of weight over the rear axle all contribute to this type of wear. If you have a lead foot, even more so.

Welcome to the high performance car world!

Before I purchased my C4S, my good friend who loves BMWs asked my opinion on which tires to get. I asked him if he liked the way the car handles...if yes, stay with the same michelin pilot sports and if not, get whatever is cheapest. He ended going with pilot a/s. I told him he was missing the whole point of his 335i coupe....oh, we'll....to each his own.

Enjoy your car, put whatever tires you want, but know you will not have even wear as these are design considerations. It will be difficult to adjust your driving style to compensate for this wear, not to mention hazardous.