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Old 01-16-2007, 02:28 PM
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jkb
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Default Rear tire wear?

My rear tires are down to the wear bars after about 6,000 miles. This cant be normal, can it?
Old 01-16-2007, 02:33 PM
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MechanicalEng
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Did you install those tires brand new 6.000 miles ago??? they should last at least 10.000 miles depending on brand and driving conditions..
Old 01-16-2007, 02:35 PM
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washington dc porsche
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mine last about 6k or so too.
Old 01-16-2007, 02:39 PM
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jkb
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Originally Posted by MechanicalEng
Did you install those tires brand new 6.000 miles ago??? they should last at least 10.000 miles depending on brand and driving conditions..
dealer installed them brand new when i bought the car 6K miles ago. cant remember the brand - it was either michelin sport PS2 or conti sport contact. but its definitely a soft sport rubber.
Old 01-16-2007, 02:42 PM
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cdodkin
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You've been using them haven't you!
Old 01-16-2007, 02:43 PM
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bet
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Originally Posted by jkb
This cant be normal, can it?
Not unheard of depending on tire, alignment, driving style, etc. Definitely on the low mileage side but within the normal range reported on Rennlist. Was the wear uniform across the tire and both sides?
Old 01-16-2007, 02:49 PM
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1999Porsche911
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If your allignment specs (specifically rear camber) are within, but on the more negative setting of the range, your rear tires will wear on the inside half of the tires more than the outside. This is normal and is dictated by the car riding on only the inside half of the tires when driving straight. to reduce this type of wear, set the camber to the minimum of specs.
Old 01-16-2007, 02:50 PM
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jkb
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Originally Posted by washington dc porsche
mine last about 6k or so too.
aha.. as long as i am not an exception to the rule
Old 01-16-2007, 02:57 PM
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MPD47
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Sounds like you drive like me. Rear tires dont last long with my alignment and driving style.
Old 01-16-2007, 02:57 PM
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jkb
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Originally Posted by 1999Porsche911
If your allignment specs (specifically rear camber) are within, but on the more negative setting of the range, your rear tires will wear on the inside half of the tires more than the outside. This is normal and is dictated by the car riding on only the inside half of the tires when driving straight. to reduce this type of wear, set the camber to the minimum of specs.
yeah i know what camber is i am pretty sure mine is within specs, but i'll check out when i get new tires.

i wonder if i can rotate existing rear tires or are they unidirectional?
Old 01-16-2007, 02:59 PM
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cdodkin
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Originally Posted by jkb
yeah i know what camber is i am pretty sure mine is within specs, but i'll check out when i get new tires.

i wonder if i can rotate existing rear tires or are they unidirectional?
unidirectional on all the ones I've seen - so you're SOL.

Was the wear even across the width?
Old 01-16-2007, 03:00 PM
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LVDell
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Pics of the tires? I am sure we could tell you exactly what the problem is.
Old 01-16-2007, 03:07 PM
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I wasn't the greatest at math, but I think the ratio is something like:

Right Foot Angle / Rear Tire Wear
Old 01-16-2007, 03:11 PM
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1999Porsche911
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Originally Posted by jkb
yeah i know what camber is i am pretty sure mine is within specs, but i'll check out when i get new tires.

i wonder if i can rotate existing rear tires or are they unidirectional?
I think you missed my point. If the camber is WITHIN specs, they WILL wear in this fashion. The only way you can reduce the wear and also maintain good handling, is to reduce the negative camber to the minimum allowed.
Old 01-16-2007, 03:40 PM
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My first set of rears lasted about 6K miles, but there are 2 factors that effected this. My fronts only went down 2/32's in the same amount of distance. I ran the Porsche recommended 44 psi in the rear and they wore out in the center with almost half the tread remaining on the outside. This is far too much tire pressure for wear and contact patch. I now run 38-40 psi. The other is I did several track days on those tires, which certainly shortened their lifecycle. Not a problems since I now have race wheels and tires. i run a lot more camber than factory specs (-1.6 front and -1.9 rear), but i am not having wear problems due to camber (inner or outer edge wearing faster).


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