Hi I am a first time Rennlist member and poster. I purchased a 2007 C2S with 36k miles from private owner 3 wks ago.Car mechanically great. Daily driver grade body, some dings and such. Has a chip, evolution motorsports air intake, and mesh kit. Interior 8.5/10. It needed new tires so I replaced the Michelin PS2's with bridgestone s04 pole position from Tire Rack. Had them installed at local indy tire store that works on alot of German and Exotic cars. I had them align the car as well and they provided the spec sheet showing the indices adjusted. I have driven 50 miles or so, and this car is all over the road. Granted they are new, but it is really squirrely in the rear end. The pressures are 43 rear/37 front per the owners manual. Tracks horribly. Is this alignment or new tires/pressure issues? The car has 1 yr of CPO left and is scheduled to go to dealer in Tampa on Nov 5th anyways. Any ideas?

 

Tires are just breaking in, there's a lot of oil and crap on them. This is normal for any tire... you need to put 500 Miles or so before they come alive.

I once made a BIG mistake and took my car tracking literally 2 days after a new tire install with may 150 miles on them, I almost crashed at the first corner, no grip whatsoever! They just need sometime to wear off the oil and crap.

Now, if you're tracking always to one side or another, it might be alignment, but most likely it's just the tire breaking in.

 

Wow quick reply! I love Rennlist! Thank you for the words of encouragement Alex. Is there any quick links to tried and true alignment specs for street?I may track the car at some point. Still figuring out how to drive it. Have owned 27 german cars of various types and performance levels over 24 years but never a 911. First Porsche a 2005 Cayenne Turbo 2 yrs ago.I seemed to enjoy more toe on an M3 I owned along with a raced prepped A1 GTI in the early 90's. Not sure about this car though. Thanks everyone for putting up with a novice enthusiast!

 

Ok. Thank you so much! Look forward to many more posts in the future.

 

I have never heard of oil on tires but they do need time to break in. My tire shop says to take it easy for the first 100 miles for the tire to settle, bead to set properly, etc.

The problem you describe is rather odd, could one or more tire be warped? I highly recommend you take it back if the problem persists after 200 miles or so after installation.

 

Sorry I should clarify.When I wrote it "tracks horribly" I should have written "It holds a line horribly on the street. I am fortunate to have a toll road with high speed (unlawfully driven at 0730 hrs) sweeping turns, and the car shifts in the rear quite a bit. I will slow down and give some time to break in. Cant help but to bury my foot in the floorboard and listen to the wail!

 

New tires have a lot of tread which makes them very squirmy. As tires wear they tend to handle better. Thats why racers shave their tires for better handling. Also, as the tires go through several heat cycles, they will firm up, just have some patience.

http://www.tirerack.com/tires/tirete...e.jsp?techid=5

 

New tires are a little greasy and don't have full grip but the should hold a line. If have the alignment checked again. Also, your pressure is pretty high IMHO. There's much debate about that.

Curious as to why you swapped tires to the bridgestones? Most people are going to the Michelin pilot super sports.

 

I agree that I'd get it checked out - alignment and pressure. The car shouldn't be doing what you describe. It should hold a line with a great deal of precision. It will get fixed for sure, I'd just get after it. Partly because if it's not tracking properly the tires are likely wearing more than they should as well.

 

My '07 C2S has identical new tires and tracks straight as an arrow. Only complaint is tire noise, which I didn't expect with this quality tire. Seems like the rears "howl" at 20-30 MPH, then the sound goes away (or cannot be heard).

 

Kind of tough to tell given you changed two variables at once. If your tire pressures are OK I'd vote for alignment. A small change in alignment (for the worse) can wreak havoc on these cars. You didn't ask them for a "performance" alignment, did you? If so, you may have too little toe -- causing the wandering.

I'd take it back and have them check/redo the alignment. I'd come with Porsche factory alignment specs in hand.

 

I have an old school view about alignments. Leave well enough alone.

If the old tires are wearing evenly, and you have good handling, why screw with the alignment. Not many techs can do a Carrera alignment well.

New tires need some break-in miles. I just had a new set of PS2s (N2) installed. Now I have a slight vibration around 70 mph. Goes away north of 80. Not complaining until I get a few miles on them.

 

I think that is it. I suspect the OP's car has a bad alignment.

 

I think this is the newest "upsell" by many installers/dealers: sell you an alignment when there's no indication you need one.

I wouldn't do anything until you have 500 miles on the tires at least. But keep the alignment spec sheet to check up if it's still squirrely at that time.

 

I'd push back on that a little bit. If the installer left one of the eccentrics loose it could be a safety issue. OP says the rear end feels unpredictable. If it feels unsafe in any way, I'd take it back immediately...