smokestack20

Finally getting around to mounting a new set of Michelin Pilot Super Sport tires on the 997. Things are still ugly here in New England with a lot of snow & chemicals on the roads so I've opted to just bring the wheels in (not the car) for mounting.
Point is when you handle each tire you can get a good look at the wear pattern etc. There are 14,000 miles on this set,(Michelin Pilot Sports) the fronts wore even and still have a little life.
The rear tires however are completely shot! That is, the inside of each tire is worn just shy of canvas (actually there's a little showing) and the outside of each tire doesn't look bad.

I have read on the Forum that the camber can be adjusted to allow for a little better/even tire wear... however sacrificing some handling.

So the Question: Has anyone out there done this? I don't expect Porsche would recommend it but the car is pretty much a fair weather cruiser so I could sacrifice some handling. [apologies to the track guys]

Thanks Ken 997.1C2S

Macster

My experience/info is camber plays no role in that type of tire wear. Rear toe is the culprit.

The car can be aligned to reduce the inner edge tire wear to the point the wear becomes even across the entire face of the tire tread and tire life can jump to 20K miles or more (based on my experience with both my Boxster and my Turbo).

I do not know what the toe in numbers should be but a good tech should know if you tell him what you are after.

You should not have to sacrifice handling or feel for improved tire life.

Both of my cars have had the two kinds (so to speak) of alignment and in both cases I couldn't tell the difference. The car felt the same, handled the same, was as stable at freeway speed (or, ahem, above) on the straight or in a turn.

The only difference I can report is tire life. My Turbo has gone through a set of new rear tires in around 8K miles vs. nearly 23K miles the only difference between alignment.

BIG smoke

While lots of tread on the fronts. How old are they? Five years? I'd replace them. Four new shoes is always fun. 14000 miles on the rear? I'd be happy with that.
Cooler temps, straight line driving, no acceleration will increase mileage.
I would say tread life is heavily influenced by the right foot.

As I mentioned in another thread. Take a picture of your perfect wheels before mounting. No scratches or dings or curbing. check for similar condition upon mounting of your new shoes.

motopix

To be honest, I've never quite understood or retained alignment numbers in my brain, but I was told the same thing 3 yrs ago when a guy I trusted aligned my miata.

I had lots of / \ in the wheels but they have worn evenly across the tire because the toe is set right.

sjfehr

Toe out will eat tires pretty quickly, and rear toe out makes the car handle really dangerously, too. Keep the camber and realign for a little toe in, which is fine. Since this is just for street use, Porsche spec alignment and camber should be fine.

And if you're not at least occasionally driving this car like a sports car, tsk tsk on you, you might as well have bought a mercedes or jaguar or something.

smokestack20

Thank you all for the response.
Big smoke.... I did replace the front tires as well. Wheels were in good condition and the installer took pains to keep them that way.

Macster, always there with good advice
Seems motopix & sjfehr agree with adjusting the toe. Gonna look for the right guy to make those adjustments.

sjfehr.... Did a little tracking in my younger days but I'm now retired along with my "heel & toe" so the car is relegated to cruising around. Agreed the car isn't driven to its potential but it still puts that $h!t eating grin on my face.

Thanks again guys K Veary

SMR

smokestak20, my rear tires are done. The prior owner of my '06 911S Cab replaced just the fronts before trading in the car, and they are in good shape. All 4 tires are Pilot Sports. I am also at a point in my life, where my 911 is not driven aggressively, but I do enjoy spirited driving from time to time. I was thinking of switching to Pilot Super Sports all the way around, even though the front Pilot Sports are still in very good shape. What led you to go with the PSSs instead of keeping the Pilot Sports. I have done some reading in the forum and remain confused about the difference, especially why the PSSs do not get the Porsche approved N rating.

sjfehr

How old are those Pilot Sports? PS or PS2? If they're more than 5 years old, replace them all regardless of how they look. If they're not, I wouldn't worry about putting PSS on the rear with PS on the front. The risk is that the balance of the car can change under certain conditions, leading to unpredictable and dangerous behavior. It's more of a risk when the tires give significant different levels of performance wet/dry or cold/hot, but these tires are so similar that the risk is pretty low. I think you'll find the car will be biased towards understeer in almost all conditions with PS on the front and PSS on the rear.

N-rating is marketing and pretty much worthless. Ignore it.

SMR

Not near the car now, so not sure if they are PS or PS2, but they are about 2 years old with less than 5,000 miles. While I am not looking for a luxury car ride (my A6 provides that), I wouldn't mind a tire that's just a bit more forgiving and quieter. Are the PSSs a good choice? And, if I can get away with just replacing the rears for now, that would obviously save a lot of $$.

SMR

sjfehr, you mention that it is okay to replace the rears with a different tire as long as they have similar levels of performance with the front tires. But, I thought that the PSS does much better in the rain that the PS? Would that lead to a potentially dangerous situation in wet driving conditions?

Macster

Some years ago I had a highly regarded indy tire/alignment shop fit new tires to my Boxster and do an alignment.

When I was handed the keys to the car I was told the alignment was done but the rear camber was at the max allowed setting. I was concerned about this and was going to insist the camber be brought to right on the money. The owner assured me the extra camber would have no negative affect on tire wear/life nor negative effect on the car's handling or road feel.

Because I trusted the shop, the owner (I had used this shop before and was quite impressed with the level of work) I accepted the car back.

Sure enough the shop owner was right. The car felt just fine and tire life was what it was with previous alignments with less camber.

With both of my Porsches over the years and a number of tires on both cars and a number of alignments on both cars the one alignment setting that stands out as the one that is most often out of spec -- in the red -- is rear toe.

Now I have to point out that the alignment I get for my cars suits my style of driving, which is strictly street driving. Also, while I "enjoy" my cars, the power and handling and grip, if you know what I mean and I think you do, I do not get all crazy with either car (at least not that often). While I could I'm sure kick out the rear of the car -- especially the Turbo -- going around a turn using just the gas pedal I do not.

If one's style of driving has him steering the car around sharp turns using the throttle I have no idea what tire wear patterns would be. Could be that no alignment could provide even tire wear given this style of driving.

smokestack20

SMR I thought the Pilot Sports were no longer available and the Pilot Super Sports were Michelins replacement. The PSS certainly seemed to be a favored tire on R-List, that, and getting a very good deal made my choice easy.

One note: I was ready to purchase from Tire Rack. Damon (a list contributor) was excellent, however I was able to save $174 going through a local dealer for the set of 4. Couldn't pass up the savings.

Despite having some life left on the front tires... I replaced them due to age.

KV

sjfehr

No worse than the difference between full tread PSS on the rear and nearly bald PSS on the front.

I wouldn't put, say, PSS on the rear and Blizzaks on the front though.

Bruce In Philly

My opinion differs from those who point to rear toe as the wear culprit (absolutely improper toe will wear tires). For me, it was the camber. I wore out my rears really fast but only on the inside all the way down to the cords.... I had no idea as the rest of the tread looked darn good (my first 911).

I had an alignment done and took out much of the negative camber in the rears and my winter and summer tires are experiencing perfect, even wear. The toe was within spec before my alignment. My rear camber is just outside of spec now.

Notice how our cars sit with obviously canted rear wheels (tops in, bottoms out). Now in your mind (and I have an active one), make the tires five feet wide. Where is the wear going to occur? Our rear tires are already really wide.

Regarding poorer handling... I am not so sure about this. Remember that car companies tweak their suspensions for performance but also safety. When I did my rears, I also had them put more negative camber in the front. The car went from boringly stable to a bit lively.... not twitchy, but more like my 2000 Boxster was from the factory. I am very happy with this change as I was a bit disappointed with my 2009 C2S's handling being pretty darn Buick like. Talk to those who track their cars and one of the quickest things they learn is to tweak the alignment. The reasons are many, but there is no perfect alignment for a Porsche. We love to think our cars are the top of performance from the factory tweaked by engineers who are monks on the weekends and only use special wrenches.... yadda yadda... but the engineers, with the marketing department, come up with a compromise that balances performance (twitchy track like), comfort (stable straight on the highway), and safety (a bit of understeer) as it is best for their target market. And note that Porsche has expanded their eyes on a broader market than just the performance-oriented enthusiast. Remember how even today, the car reviewers talk about the dangers of a rear engined Porsche? Do you think Porsche wants to give any fodder to this line of dialog?

YMMV.... this is just my opinion.

Peace
Bruce in Philly

smokestack20

Bruce,

Yup, The camber setting was my original thought for my tire wear. Mine was exactly as yours.... the inner rears were worn to the canvas.
No expert here, but camber and toe make some logical sense to me for that type of wear.

Hope to find a knowledgeable experienced local guy to solve the problem. At the very least I have some reference from all you list members. Thanks!

KV