sig_a

Shannon:

Could it be that at least a small portion of you spin problem has to do with suspension alignment?

You may think about calling all of these guys in and around Cincinnati for advice:
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http://www.performance-alignment.com/ (in Blue Ash)

Bill Brocksick did my alignment and corner balance one year ago in March. Since then I have driven twice to Mid Ohio and twice to Putnam plus 1000's of street miles on the NT 01's. Bill has been doing suspension mods and alignments on porsches for 30 + years.
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Farler Performance in Franklin Ohio, near Middletown
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http://www.wrighttuning.com/ (Batavia)

Wright team finished third at 24 hours of Daytona earlier this spring.
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Generally speaking, with such few miles on new tires, your rear tires should not show much more tread ware than the front. Perhaps 2/32" at most. And it has nothing to do with driving to the track on R compound tires.

911vet

Hey Sig, thanks for the info and the input. The car seemed to be handling very well in general. The spins were definitely driver error issues (one from my friend, one from me).

I did have the car aligned just before going to the track. I've got the computer print out and I trust the shop. So I'm sure that I'm even side-to-side. But I don't have nearly as much neg. camber as y'all are indicating I should.

I'm going back next week to get the situation re-evaluated and decide on new tires. The MPSCs are going out of stock so I may be stuck getting something else.

Ray S

+1

I have used about 6 sets of MPSC's on my 986 and I have never seen wear like that on my tires. FWIW, I drive my car to and from the track on the MPSC's and I utilize fairly mild (for the track) alignment settings so I don't eat my street tires.

I generally get about 6-8 track days out of a set on MPSC's

kgorman

Any chance you have pyrometer data from those tires?

Depending on how hard you drive you may find that you get more grip out of something else with a car that weighs what yours does (not as heavy as a GT3 for instance). I found the MPSC worked great on heavier cars where it was easy to get them up to temp. Tom is right, you have to get them really hot.

Get Nittos or R888's or something that require less camber and you can drive to the track on them. Normally I would say RA-1. They were the perfect tire for drive-to-track type cars. Too bad they are gone. ;-(.

Flying Finn

I have -2.5 & -2.9 on my 993 and it's fine. Obviously the inside wear more when on street but then at track, you'll wear them pretty evenly.

As already said, crank more camber and you should be fine, pyrometer is a good way to find out what the tires are going through when at track.

Oh, and less spinning always helps too!

Larry Herman

I just have a lot of experience and have a good understanding of the subject. I also don't make "expert commentary" on things that I do not have first hand knowledge of. I am under-appreciated at Riesentoter.

himself

+1. There is no reason for your expensive "Cups" to have such uneven wear. Fix your alignment.

I actually had a similar problem many moons ago [cording the outside of my track tires due to lack of negative camber]. My first solution to saving my "expensive" track tires was to set up my car at -2.0 F and -2.5 R. Then I got a cheap set of street rims and ran Sumitomo tires until track days. Ultimately, I stored my track wheels at the track and just drove my cheapo streets to-from. Actually, I still do that!

And you can definitely get a backup set of rims for less than $700.

-td

Phokaioglaukos

Don't say that!

StoogeMoe

Besides a possible alignment issue, I think any tire would be rendered useless after a flat spot like that, whether you got to the cords or not. The vibration alone would make the car undrivable.

Like others have said. Don't do that!

analogmike

If those were the Hoosiers we ran several years ago, you would see AIR where those belts are.

racer

Depending on the mods made, you *could* have trouble getting the camber you need. Short of camber plates or a good come-along to the shock towers, my SC couldn't get enough negative camber with otherwise stock like components. I too would wear out the outside edges of the fronts, luckily they wore at about the same rate as the sliding rears would

Also, it sounds like the small amounts of street driving you do would impact the tires very little. Excessive TOE setting (ideally a bit of toe-out in front) will likely kill your tires faster than the negative camber amounts being discussed here).

Porsche917K

No. I ran 3-3.5 on my 964 that saw plenty of street time. You are basically trading street wear for track wear, but you would be surprised that your wear is actually not that bad with a more aggressive setup. Also try Nitto NT01's. They are a greap r comp that wears better than most others.

wanna911

NT-01's are a great suggestion, they last for a long time.


But look how much of the contact patch you are NOT USING!!!! This can be a contributing factor to your spins because during cornering, instead of using (for example) 10 inch wide wheel you might as well be using a 6.5 inch wide wheel.

If you aren't using that part of the tire, it will wear prematurely no matter what kind of tire it is. Some other tires may last longer, but you are only masking the problem, not fixing it. Street tires will take a lot more abuse though, so if you can't get more camber, I would say your car is street tire only.

If it is your home track, move to streets for now.

911vet

To clarify: The tires DO NOT have uneven wear. They are worn evenly. There is ONE spot shown in the picture that is worn and corded. It was from a spin.

The tires did not fail because of alignment. The "defect" is focal, not concentric. I'm sorry I didn't make this more clear in the original post.

I appreciate the input about MPSCs and alignment. I was not aware of the importance camber might play with this particular tire (or R cmpds). It will factor into my decision about buying them again.

911vet

I understand what you're saying. But these tires had essentially 1 drive to the track and 1 day on the track. So the LACK of wear you see on the inside may simply be from low miles rather than lack of neg. camber.

The spins were not a setup problem, they were pure and simple driver errors. The car handled beautifully before the tire damage. But wow are you right about it being undriveable after. The vibration made it unsettle to the point I couldn't judge the "feel" of the car anymore.

Not my home track. This track has abrasive pavement. My home is Midohio and it's smoother. I have 3 DE left this year: MidOhio and two at Bluegrass (I hope).