Bodhi

Buzz, Your post appears to assume that the alignment on your car is within specifications. Did you get the current alignment numbers? If so, what are they?

In any event, 8-12k is normal on rears. In addition to camber, Porsche runs with a decent amount of toe in the rears, which also affects tread life. Keep those within spec unless you like a really loose back end.

PDQ PDK CAYMAN S

Porsche will do a free alignment up to 2,000 miles and the damn dealers do not tell you that! And they even get paid for it. I had mine set for max tire life and they lasted 15,000. I do track the car with slicks and they are doing great and wearing well. The tires will wear out on the inside a bit sooner than the outside.

Buzz911S

Thanks for the input guys, but I don't see other 911 rear tires running on the inner sidewall. Yes, I did let some air out for autocross.... but y ou really don't need to do t hat. I know about expected tire life and I think you guys give up to easily. I see some have their alignments checked when the car comes in. I expected Porsche to check that when my car arrived. I'm not crying about the money.. that isn't the issue. I just think Porsche should realize that not everyone races these cars. So, why the aggressive alignment? I have negotiated all I can with th e dealer. If I buy new tires, they will realign the rear for maximum tread wear. Their wheel man tells me he can get up to 15k out of the rear tires if it is done properly. I went and checked the tread again and it is not down to th e wear bars yet. I know they would have gone another 2k miles if they weren't running such severe negative camber. So, I ordered original tires..... $400/each. The dealer will realign the rear for maximum tread life free. After we noticed the threads hanging out of the sidewall, I drove the car from where the pictures were taken back to my garage and my poor pcar has been sitting there for two weeks. I am driving my TT Stealth RT. After getting out of the Porsche, this Stealth feels like driving a volkswagen! Ha! I don't have any idea what the numbers on the alignment are. It hasn't been checked yet. There's no doubt in my mind that the rear is out of spec. If it is, then I'll have to argue more with my dealer. After I wear out this set, the front's should be gone too. Then, I changing to a harder compound tire.

Can anyone recommend a good ZR rated tire ? Bear in mind, I am still going to race autocross with it... but I really don't think it wil make any difference in handling at that speed. My average speed at the last race was 49mph. And, I nailed first place in Novice. I should have sandbagged more. Now I'm kicked up into a really fast class. 90% of my driving is on the street with an occasional aggressive run to blow things out. I'm lucky to have a friend who owns a private airport. When things aren't busy, he lets me make a couple of passes down the THREE mile long runway. It is on that runway that I ran it 160mph. I ran out of room and had to lift. That's fast enough anyway!

Anyway, that's my story and I'm sticking to it. Heh Heh H eh.......

Bob Rouleau

Your front and rear tires should be the same. With respect to your wear, note that toe also affects the wear. It might not be just the camber. If you "race" the car, inadequate cambere will wear the outside shoulder area rapidly, everything has side effects. Ultr high performance tires wear faster than more utilitarian ones. If you want long life, buy tires with a treadwaer rating of 400 - just don't expect the same grip as you get from your sticky tires with a treadwear rating of half that or less.

Best,


Regards,

Buzz911S

Thanks Bob. No, I have owned high performance tires for a long time and I'm not about to put two different kinds of tires on it. When this set is worn out, I will change to a different tire with harder compound. I am aware that a harder compound tire will be a lot looser.... but I believe the toe is out of spec also. I believe the tires are toed out too far, thus adding to the wear on the inside edge. It's like I'm dragging them down the road. On some roads I can look in the rear view and see two stripes of rubber on the ground behind me.
That's tire scrub! No doubt about it. Thanks for your input. I was looking at the continentals ... same ZR rating. Does anyone use them here. KNow anything about them? I really appreciate the help.

Buzz

1999Porsche911

Your front and rear tires SHOULD NOT have the same wear at all. As I said before, Porsche's allignment specs REQUIRE all rear tires to wear out on the inside half before the outside. It's a simple fact. Those that have less wear on the inside do not have as an aggressive camber setting as the specs stiplulate or are running extremely outside of the recommended tire pressure. The straighter you drive your car with a negative camber, the faster the inside half of the tires will wear out. There is one way, and one way only to make the tires wear more evenly and that is to reduce camber settings on the rears. If you track the car or otherwise dive into corners aggressively and frequently, the tire wear will be different.

Therefore, if your alignment if correct you WILL wear out the inside of the back tires long before the outside half. If you do not, you alignment is definately out of spec.

Try walking knocked kneed for a few days and let us know if you get blisters on the inside or the outside of your feet.

H20NOO

First, from the looks of the outer tread, your tires were toast. Second, as one of many measures intended to eliminate the traditional 911 off throttle oversteer problems, Porsche is very aggressive with the negative camber in the rear. This not only keeps the car safer to drive but allows the rear to stick much better which is WHAT A SPORTS CAR SHOULD DO... Keep in mind, these cars are sold as high performance vehicles yet the suspension and alignment are still highly compromised for daily driveability and comfort.

I have 7600 miles on my '06 997S including 225 miles at the race track and an autocross and my tires look like they have another 1000 miles or so to go. I expected this when I bought the car.

In addition to having the car re-aligned for better tire wear, I suggest buying new tires that have a much higher treadwear rating than the OEM tires. The alignment will make a big difference. Go to www.tirerack.com and look for similarly sized tires with higer treadwear rating. Michelin PS2's are rated at 220 although I think they wear more like 150.

Best of luck,

MC

arenared

My 2 cents: alignment is like tire pressure. It is not a set and forget kind of deal. You need to check both. The rears are particularly susceptible to going out of alignment. Also, the factory alignment specs are so wide as to be useless. Just because it's in spec doesn't mean a whole lot.

Also, it doesn't matter how much you paid for your car. These ultra-wide, low-profile tires are very sensitive to alignment and tire pressures. Everything is a compromise. 8K looks reasonable to me. What you need to do is go to an alignment shop that knows these cars and does precision/race alignments based on how you drive what you want.

I do agree about SALES people. Most are stupid and are merely regurgitating 3rd-hand information. A dealer is never going to warrant the tires or alignment. They have no idea how many burnouts you do or how many pot holes you drive over. If aligning the car to YOUR needs does not provide satisfactory tire wear, then either accept it as a cost of driving a high performance car or get one of the better of the higher tread wear tires.

Good luck!

Buzz911S

I've run high performance cars all my life. Believe me, I know better than to change brands on only one end of the car. But I do appreciate your noting it.
I live for speed and competition. I raced pro motocross for years, and did quite well at it. I raced 140mph outboard hydros until I flipped over backwards a top speed. My passion is racing sports cars. I've done if for a long time in a variety of cars. But, I fell in love with the new 997's and just wrote a check and drove out! I should have studied the car more.... but I can't think of a car at this price that is cheaper to maintain. I just need a realignment and I think the best thing for me to do is not to burn bridges with my dealer, but accept the deal they offered. I may be crazy, but I'm not stupid.

I'll burn the Michelin's off of it front and back.... and then go to a harder compound rear tire on all 4 corners. My front tires are wearing great. They, of course have "rollover" tread wear on the outside treads, but I can run higher air pressure to make them run more on the centers for daily driving.

Here is what I've decided to do. I'm buying a set of strong wheels, maybe just steel wheels for the car all the way around. I'm going to mount sticky slicks on them, and when I go to race, I will put the car on my lift and change them. I have a car trailer, so I can tow it to racing venues. That's only once a month here with SCCA races. That seems to be the best investment to save my street tires. When I go to Sebring, I'll just trailer the Porsche on it's slicks.

The one t hing I didn't understand... and you guys help me out here. When I called about my tires being worn out, I told the service dept. that the car would not make the 75 mile trip. I can't use Porsche Roadside Assistance, because I don't have a flat tire. This guy literally told me to cut the inside of the tire with a knife, or even better, just go out and do burnouts or spin circles until one of them came apart!!!!! I can't believe he said that! What if I spin a circle and a tires blows.... it will probably fly apart at that rpm and destroy a rear fender. Where do they get these guys?





Actually, they did give a woman a new set of tires after hers blew out with only 2700 miles on the car. YOu're correct about them not knowing how I've treated the alignment though. . I can accept the tire wear, but I k now I can make it better. If it wears them out anyway.. tires are the least of my concern. I'm just not satisfied with a lying salesman and a crooked service manager! LOL! Cut the tires? That will be noticed in a nano second!

Oh, and ....bad timing on the dealership to send me a questionairre about how satisfied I am with the car and the sales people. I'm not going to burn any bridges, but I am going to be honest. I wasn't treated very well. Maybe it's because I bought the car wearing a Ferrari shirt and jeans.

brad@tirerack.com

8-10k is all you can expect from a set of rears on these cars. That's the average of what I see, and what I tell people buying.

dstrimbu

Yepper, at 5.5k it looks like about 2.5k remains on the rears... and I'll be up to South Bend to see you in the spring, Damon.

That being said, it might be frustrating to replace $1k in rear tires every 8k miles, but that's the price of admission. Talk to an NSX owner if you want to hear more ridiculous wear numbers.

I will say that I've never driven anything else even remotely like this car in my life, and if that's what it costs to keep this grin pasted on my face, so be it... <g>

-don

mauijim

Right on dmoney. Maybe saving other lives as well. Referencing the original post: I want to know how many on this forum track their cars AND haven't checked their tires for 8k miles! How many haven't checked their street car's tires for 8k miles? Probably not many. This thread is not about tread wear - it's about high want, low effort.

ty328

Yes! You need to redo your alignment, here's my photo. I already have over 1400 mile on my, but never took my car to any race track.

mglobe

Some quasi scientific data on rear tire tread life.

https://rennlist.com/forums/997-forum/270423-rear-tire-treadwear-poll.html

Ian C

Don't want to sound like a smarta** here, but if I drive a performance car like a 911 then I make sure that every week I check the tyre pressures by hand and visually inspect the tyres themselves. Takes 5 minutes.
Buzz911 - I'm a little confused about one thing: you say that you've raced this and raced that all your life, but in your earlier post you say that you were entered in the Novice Class?