Rear tires gone in 1,500 miles

How is it even possible that my new rear tires, Continental Extreme Contact Sport, would be gone and down to the cords in 1,532 miles. The fronts look fine. One rear went flat. I swapped it for the mini spare, which was not fully inflated and only lasted a couple of miles before shredding...had to get a tow. I had the wheels aligned this spring after having the rear control arms replaced on my '02 C2 Cab. A friend said it happened to his Boxster, and it was rear wheel alignment. The wear across the other rear looks even but all tread is gone...a slick. Any thoughts about culprits other than rear wheel alignment? New Michelins on order...an expensive summer for tires!

Alignment, rear wheel drifting, tire spin?

Either your are burning rubber up and down the road, or your alignment in way the hell off. Is it possible you have another person in your home who may be taking the car for a joy ride here and there and showing off by peeling out all over the place?

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I'm a sedate 72 year old who only occasionally is heavy on the gas. I don't burn rubber, and no one else drives the car. I do like corners but have not abused this car in any way. Gotta be the alignment failed, eccentric bolts loosened, something like that. I did have an issue once after the car was up on a lift...the eccentric on the left rear loosened by itself, and the car was scary to drive! Maybe Loctite those alignment bolts?

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Loctite cant hurt for sure. That is a shame, I would be talking to who ever did the alignment... BTW I love the color!

If its even wear then its either your tire pressures are wrong or the way your driving it. Or it could well be defective rubber compound.

Seriously, contact Continental and have them look at the tires, sounds like defective compounds/manufacturing defect.

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FYI. In the future, with a flat rear tire, you move your good front tire to the rear, and then mount the space saver spare to the front. 50 MPH max.

I am running the same tires since January 2018. They have performed well and still look very good, I've put over 7,000 miles on them. I would be contacting the place I bought them from and Continental directly. Your wear experience is super a-typical.

As others have said. Correct Tire pressure is very important as is the alignment. Periodically check the spare as it's useless if not full. They do make locking plates for your eccentric bolts. I'd get new ones. I suspect the last place that did your alignment never torque them properly...

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Wow, I didn't read the manual about flat rear tires so I didn't know this. I would have had to think to jack the front first and swap the space saver there before lifting the rear. I'll know for next time. I was only going 25mph with the space saver on the rear, but there is a lot more weight on the rear than the front!

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I'm betting on an alignment issue...pressures were good. I'd rather believe in defective rubber but find that hard to believe. I will contact Continental.

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I talked about tracking my 1999 C2 in another thread. It became obvious on the track that the suspension was worn out, including the bolts you mentioned. The speed shop that replaced my suspension is very familiar with 911s. They stated that it was not uncommon for these bolts not to stay torqued. On one of their race cars (not a 996), they replace the bolts as part of normal maintenance after every third race. My loose suspension allowed the rear tires to pivot from side to side under load. It was a strange feeling on the track. Uncontrolled rear wheel steering. Sounds like you are having a similar issue. Rear tires also didn't last as long as the fronts. About half as long. Sticky rear performance tires are good for about 3 hours of track time.

That's best. But, as stiff as our cars are, you can lift from the rear, and the front will also come off the ground.

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Either defective tires as others have said, or someone snuck in at night and swapped out you new conti's for some old worn out ones... If they're really like "slicks" after 1500 mi. there's somethin' fishy going on...definitely no reasonable explanation for such...

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From what you've previously mentioned it cannot be the alignment as you had even wear on one tire. And if it was the alignment one tire would be good ( even wear tire with no tread left) and one bad ( bad aligned wheel )

Defective tires (rubber) are a possibility although rare. What's the tires date stamp out of curiosity?

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The car is at the shop, so I cannot see the date code. I'll check on Monday.

Regarding alignment, one thing I've noticed, and had others confirm is that when you go over a big bump and the car seems to want to "go a different way", you probably need an alignment. Those were the symptoms recently and after the alignment, it tracked true after that.

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Date stamp is 3817, just one year old and not the problem! Hopefully, I will hear today if Continental will do anything for me.

Not sure who you have looking at the car (not many good options in Vermont), but Jason at Bullfrog Automotive in Milton is a well reputed indy. He's a PCA member, and I've heard lots of good things about him from people in the club and other mechanics in the area for Porsche specific work. Oh, and I've had alignment work done on my 996 at Sterling Auto Works on Airport parkway. They did a good job setting my suspension to GT3 specs (spec that I provided them).

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Hi CDS72911, So far I've been using Rick Cabell in Burlington. I know he and Jason collaborated on changing my IMS bearing last fall. I've known Rick for many years. I'm unsure who Rick had do my wheel alignment but his shop is close to Automaster, who also do alignments. I still have not looked at the car while on a lift to see if I can see any suspension issues. I'll bring the car to have Rick take a look once I get some new rubber. Still, my money is betting on loosened eccentric bolts, at least one because that was an issue I had before. We shall see. The tire shop is also going to take a look. On another note...that mini spare is not easy to find. The tire shop found one on line for $170, wheel and tire, and I had them order it before I even looked at Porsche parts dealers. No parts dealer I looked at had any 996 spare tire! Thanks for the heads up about Sterling and Jason. I live in Montpelier and am looking for other pcar owners to connect with. Please send me a message if you have any leads!

TireRack has replacement temporary spares for $95. https://www.tirerack.com/tires/tires...num=195MRCST17

^^^ The 115 is 2.4" larger in circumference than the 105 it replaces so I am not sure it will fit without rubbing on the hood. When I searched last year, I could not find anybody that could confirm it fits the C2.

Checked for perished rubber in suspension setup. Sometimes they only show deflection under load but in static state are fine. Example if your tortion arm bushing is worn the wheel can totate to the point where wheel /tire can make contact with the arm. This can easily destroy a tire due to toe changing Ask me how i found out.

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I replaced the rear control arms this spring because of perished rubber and had an alignment done afterwards.

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Yes, this calculator says 2.32" That's about a half inch taller than the full sized front tires:

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Did you check the thrust arm bushing's?

I can really sympathize with you. I had a set of Michelin Cup 2's that wore out at 4,000 miles on the rear. I am also 71 and not a "lead foot" but do push it into corners. Got no help from Michelin or the guys at America's tire who recommended them. Had my alignment done even though it supposedly wasn't bad. I eventually put it down to soft rubber, but I have also backed off in the corners somewhat.

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Thanks for the sympathy! Even the stickiest rear tires on my motorcycles would last 5k miles, but 1.5k is crazy! Gadsby: I'll have the shop check the thrust arm bushings.

ding Nice shave Skived on wheel well lip Result of toe change. The trust arm keeps the control arm in the correct orientation which is perpendiculat to control arm mount, the rear toe link fixes toe position relative to the control arm. Under load the tortion arm can allow deflection of the bushing in both the thrust arm and control arms both bushings. Solid toe links allow no rotation tword the rear. As you can see from this image worn thrust arm bushings can allow the wheel to rotate to an extreme (toe in) position when highly loaded. The ding in the arm is from the inside wheel rim lip, there were multiple dings in the rim, i caught it just as i installed new tires where it skived the outer edge in the wheel lip which can only occur through excess wheel movement laterally. You'll find it, somethings wrong which changes wheel travel orientation. Focus in under load not static.

I'm in a 911 now but two summers ago with my boxster I went through a set of rears in one summer. took it in and had the alignment gone through by someone WHO KNEW HOW TO DO IT and it was bad. new tires and new alignment and it felt like a new car. handled much better, drove smoother, straighter etc. just contributing about my experience.

This is what the blown tire looks like: That's one ugly tire! Sure looks like one side wore faster than the other. The second rear tire is still on the car, and it appeared to be evenly worn. I may be able the see that tire off the car later today. Gadsby: this does not look to me like the kind of wear you experienced. ​​​​​​​ttt123: Hopefully the car will get towed to the shop tomorrow, and we will have more info about the alignment and suspension.

hope it gets figure out for you.

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Pretty consistent: check how much camber and toe?

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My alignment was a little off after replacing my front lower control arms. In 2000 miles my inside shoulders were toast. Since then I have new tires with 7k miles and they still look new. You might be surprised how fast a poor alignment will ruin your tires. In my case the toe was equally pointed out, so I didn't feel much pull unless one wheel was more or less loaded than the other.

My car is now at the shop where the suspension will be examined before getting a new alignment. The old rear tires will be shipped off today to Tire Rack for their examination. One thing I noticed yesterday as the car was sitting on the tow truck is that the exhaust tips seemed to be lower than usual...maybe an inch of gap. I understand that may indicate aging motor mounts. Would that have any impact on extreme tire wear?

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Worn motormounts will have the movot moving pretty free in the back which would feel like the motor setting after the car sets in a corner, kind of like a thud.this is also what the engine actually hangs from, easy to check and change. Each one is 3 bolts.check tranny mount while your at it but should have no plausable effect on what you experienced. i included a pic of solids and semi solid kounts. I run solids for the track but are very loud inside.

All this alignment talk, I am curious as to what you guys are paying for one? Im thinking this might be a dealer only situation, Im guessing a place like Town Fair Tire isn't going to do it properly lol.

Mine cost $130 for a weighted 4 wheel alignment in Delaware. Its a local shop that asked the most important question.... "how do u plan to drive the car?" If u want it set staight to factory spec anyone can do it. If u want it to perform based on upgrades u need an indy with porsche experience.

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Thanks

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I cant imagine how worn motor mounts could result in accellerated tire wear. They�re easy to swap out though.

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Thanks...another winter project!

I just paid $179 for my alignment at the local Goodyear place close to my home. It was set to stock settings for now. Motor mounts are probably a 30-45 minute job. I need to do my own. I want to go with Rennline motor mounts since I installed a set on Monday. They're REALLY nice. The semi-solid ones are tunable.

I do most of my own work like this week its a turbo refresh. But when i use a shop its one that specializes in porsches, that know all the details i may not. They do my corner ballancing, alignments along with being a main sorce for my parts. Develop a good relationship w your local indy that can handle it, hopefully the building is packed with them at night like Fisher Motorsports.

Just curious if worn lower control arms can cause this ? My front end has been squeaking so I applied some lubricant into the bushing boot. It stopped the squeaking but I have noticed a vibration at highway speeds coming thru the steering wheel. Could these worns bushings cause the vibration and ultimately the tires to wear prematurely ?

My shop called last night to say all suspension bits look fine. Everything is tight as it should be. They are taking it in for an alignment today. Will keep you posted.

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Getting close to an answer, make sure report shows you before and after.

Another update. The shop emailed me to say the motor mounts were fine, but the bolts that hold the rear subframe to the car were not 100% tight! Under load this could cause the rear suspension to skew a bit. He could not explain how those bolts became loose after the car left the factory as they are never touched. The car has an appointment tomorrow to get an alignment by the only Porsche trained alignment guy in Vermont. I picked up my replacement spare tire and wheel this morning. The wheel and tire came from a salvage yard, are the correct size, and have 60 psi in it. Gadsby: Are your rear tire air pressures low? Shouldn't they be 44 psi? It sounds to me like we are making some progress!

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A bit of advice, buy a small 12Vdc air compressor and keep it in the frunk. Best 20 bucks youll ever spend when you get another flat. Also, generally speaking, the emergency spare should only be used in an emergency, like stuck out in the middle of nowhere type of emergency.

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Good idea on the mini compressor. BTW, I was in the middle of nowhere!

Just heard from Tire Rack...they are crediting me $480. A little faith is being restored!

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I meant like middle of no where with no cell phone reception type middle of no where. Main reason (in my opinion) is these tires are old AF by this point and new one cant be found.

RngTrtl, you just described much of rural Vermont. I live near the largest municipality, and I still lose cell signal multiple places on my short commute in.

Alignment didn't happen yesterday. My wife and I are going on vacation out of the country for a couple of weeks. I will update the results of the alignment once I return. Thanks for all the good tips, thoughts, and replies!

Update...Just returned from a 10 day vacation in France and picked up my car from the shop in Burlington. The good news is the car drives great, feels very planted. The bad news...no smoking gun. The previous alignment was close. He did find that bolts holding the subframe to frame were not tightened to spec, and that "could" have contributed to the tire issue?? My mechanic was also very impressed that Tire Rack so easily gave me back $480. I did not have to fight them at all, just returned to them the 2 rear tires for their inspection. They immediately paid! That has not been his experience over the many years Tire Rack has been in business! He thinks there may have been an issue with those Continental tires. I will never again assume tires with 1,500 miles on rears are going to be good. When I enter the car, I always look at the front tires not the rears. That will change now and I will religiously check pressures. Anyway, I'm back before the foliage peaks and have a few more great drives ahead before the snow flies!