Do I have the right wheels and tires?

[boxsterfromhell]

I bought my 1997 65,000 mile Boxster at the end of November, AS IS. One of the main reason for purchasing this car was for the 19" mesh style rims. Within a couple of days of my purchase, I had to replace the two rear tires as they were bald and held no traction in the rain. I also noticed in dry conditions, the rear end of the car was squirrelly. I purchased a couple of decent used tires until I had the money to buy a brand new complete set of four. After buying those tires, I had a rear lower control arm and a rear strut replaced, both on the same side. Within weeks, I had to replace the rear tires again. That time, I had the car aligned. Less than 3 weeks later and I had to purchase yet another set of rear tires. I took the car to be aligned again at a reputable place referred by my mechanic. Less than 3 weeks later, I had to replace the rear tires once more. Three weeks after that, I had to replace the tires again. That's five sets of tires in four months!!!

It's been two weeks since my last tire purchase and it is evident that they are considerably more worn than the day I purchased them. Last night while driving on the highway in the high speed toll lane it began to rain. The rear of the car began to swerve all over the road. Needless to say, it was very unnerving for both myself and my passenger.

My mechanic is beside himself, as he sees nothing wrong with my rear suspension other than what was already repaired.

Used or otherwise, why is my car eating tires so quickly?? Why am I unable to control the rear of the car in the rain? I currently have 245/35/19s in the front and 285/30/19s in the rear. I have also put on 295/30/19s and 275/35/19s. At this point I am afraid to spend alot of money on brand new tires until I can be assured that purchasing used tires is the source of all my troubles.

Any feedback is greatly appreciated!!

[Mark_T]

Those are absolutely not the right rims for your car. The suspension on that model year is not designed for anything larger than 17" rims, and running 19's could well be unsafe. If you do a search you'll find a few threads on the topic in this forum.

Get some 17's and run 205/50's on the front and 255/40's on the back. It will handle and ride much better. I'm going into my third season on the same rubber (Michelin) and I still have loads of tread left.

[stephen wilson]

19's won't cause the problems you're seeing. Something is worn out or broken. Take it to Mechanic who specializes on Porsches, Pedro is in Florida. Is this your only car? I would not coutinue to drive a car in that condition, especially with the cost of so many tires!

[thstone]

Some thoughts:

(1) My experience with used tires is that they wear very quickly. Not in three weeks, but they do seem to wear out awful fast.

(2) Has anyone checked the 19" wheels? Out of true?

(3) Borrow a set of 17's with stock size tires from a friend, local mechanic, or a forum member near you. Is the rear end still loose?

(4) Mechanically could be bent suspension, wheel hub, etc. Have another mechanic or **gasp** the dealer look at the mechanical bits.

Let us know if you learn anything further.

[Johnny Danger]

First of all, what brand of wheels are these ? And what are the specifications (i.e. width and offset) ?

[JFP in PA]

You need to very carefully examine the area where the forward engine bulkhead meets the rear chassis members, looking for deformation and particularly evidence of cracking. This area, along with the rear suspension mounting points were significantly strengthened in the later cars after Porsche discovered wheel diameters larger than 17 inch over stressed them on the 97’s, causing flexing, cracking, and potential failure. This was discussed in an article not too long ago in Excellence magazine.

I know that this response will cause a litany of “I run 57 inch wheels on my 97 with no problems”; but once you have seen on of these cars start to flex and come apart, it is pretty chilling. I’ve also read that one of the dead give away’s that something is wrong is that when you try to jack up one side the back end of the suspect car, it tends to twist before picking up both wheels on the same side the way an intact car does.

[stephen wilson]

True, I should have been more clear in my post, the wheels themselves aren't the problem, the damage they may have caused is another story.

[mikefocke]

to correct the problems that exhibited with spirited driving with wheels larger than the stock 16" or 17" option in the '97.

18” wheel option with rear chassis reinforced to accept new wheels. Rear body structural change included redesigned wheel wells and coil spring mounts, lower engine compartment bulkhead, rear wall cross-member and rear axle mount reinforcements.


It could be that the basic body structure that the rear suspension is hung from has deformed and is flexing and thus throwing the suspension geometry off and you are essentially dragging those rear tires across the pavement and abrading them to death.

Good luck. And there is no way I'd drive it before a true Porsche expert tells me it is safe. I've been driving a car watching through the rear view mirror as my suspension parts bounded along behind me off the road..it isn't fun...or safe.

BTW, one of the downsides of 19" tires is cost.

[WhipE350]

All good advice. Have all 5 sets been used? 295/30...I didn't even know that would fit on a 97'. Anyway ya find a good Indy, I think your description of how it drives in the wet is a clear indication something is really wrong, as Mike says, "dragging" sounds about right.

[boxsterfromhell]

Originally Posted by Johnny Danger

First of all, what brand of wheels are these ? And what are the specifications (i.e. width and offset) ?

19x8.5 and 19x10.5. Honestly, I do not know what brand. I will attempt to post a pic of the wheels. Being new to this site, I am still navigating my way around it.

[boxsterfromhell]

Originally Posted by stephen wilson

19's won't cause the problems you're seeing. Something is worn out or broken. Take it to Mechanic who specializes on Porsches, Pedro is in Florida. Is this your only car? I would not coutinue to drive a car in that condition, especially with the cost of so many tires!

My mechanic is a Porsche specialist. Claims he's been doing it for over 30 years. He's had it up on the rack many times with me under it. Neither of us have seen anything out of the ordinary other than the items already mentioned.

[boxsterfromhell]

Originally Posted by mikefocke

to correct the problems that exhibited with spirited driving with wheels larger than the stock 16" or 17" option in the '97.

18” wheel option with rear chassis reinforced to accept new wheels. Rear body structural change included redesigned wheel wells and coil spring mounts, lower engine compartment bulkhead, rear wall cross-member and rear axle mount reinforcements.


It could be that the basic body structure that the rear suspension is hung from has deformed and is flexing and thus throwing the suspension geometry off and you are essentially dragging those rear tires across the pavement and abrading them to death.

Good luck. And there is no way I'd drive it before a true Porsche expert tells me it is safe. I've been driving a car watching through the rear view mirror as my suspension parts bounded along behind me off the road..it isn't fun...or safe.

BTW, one of the downsides of 19" tires is cost.

WOW...by far the most sensical response as far as I can interpret. But why couldn't my mechanic who has supposedly worked on Porsches for over 30 years have determined this??

[boxsterfromhell]

Originally Posted by JFP in PA

You need to very carefully examine the area where the forward engine bulkhead meets the rear chassis members, looking for deformation and particularly evidence of cracking. This area, along with the rear suspension mounting points were significantly strengthened in the later cars after Porsche discovered wheel diameters larger than 17 inch over stressed them on the 97’s, causing flexing, cracking, and potential failure. This was discussed in an article not too long ago in Excellence magazine.

I know that this response will cause a litany of “I run 57 inch wheels on my 97 with no problems”; but once you have seen on of these cars start to flex and come apart, it is pretty chilling. I’ve also read that one of the dead give away’s that something is wrong is that when you try to jack up one side the back end of the suspect car, it tends to twist before picking up both wheels on the same side the way an intact car does.

Ahhh, and like Mike's response, your's too makes complete sense. I am no stranger to owning luxury sports cars, although this is my first Porsche. I just don't understand why no one has been able to diagnose my problem after 5 months, wheras in one day, I have gotten so many amazing armchair results!!

Thank you.

[boxsterfromhell]

Originally Posted by WhipE350

All good advice. Have all 5 sets been used? 295/30...I didn't even know that would fit on a 97'. Anyway ya find a good Indy, I think your description of how it drives in the wet is a clear indication something is really wrong, as Mike says, "dragging" sounds about right.

Yes, all five sets were used. As stated in my original post, I had just bought the car and wasn't prepared to dump money into tires just yet. And when the first set of used tires were destroyed after a few weeks, I decided to stick with used until it could be determined why the problem was occuring to begin with.

And as far as the 295/30s...LOL, that was an accident. I had to use my Dad's truck to pick them up and deliver them to a tire place to have them installed. When the car was in the air, the tires rubbed against everything. However, when the car was on the ground it was ok. Needless to say, those tires lasted me two weeks. Shortest lifespan by far!!

[ekam]

You bought used tires... well that might just explains it.

[blue2000s]

Originally Posted by ekam

You bought used tires... well that might just explains it.

You're driving on used tires

[Johnny Danger]

Originally Posted by boxsterfromhell

19x8.5 and 19x10.5. Honestly, I do not know what brand. I will attempt to post a pic of the wheels. Being new to this site, I am still navigating my way around it.

A 10.5 inch wheel is a red flag right there . I'd love to know what the offset is in order to make that wheel fit. Is there a large spacer involved ?

[ekam]

Originally Posted by blue2000s

You're driving on used tires

But where do you even find used tires in the first place? It's just like underwear... who sell them used?

[stephen wilson]

It's as easy as going to your local tire/alignment shop. I bought some used tires for my Toyota 4x4 to get thru inspection. They go on for 1 day every two years, then back in storage!

[Johnny Danger]

Originally Posted by ekam

But where do you even find used tires in the first place? It's just like underwear... who sell them used?

On occasion, I've seem some low mileage thongs like this one come up for sale on ebay .