Rear tire wear pattern
Thread Starter
Teching In
Joined: Jan 2007
Posts: 38
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From: MA
Rear tire wear pattern At the beginning of this season I replaced my kuhmo 710 265/45/16's.
On the rear, the outer third of the tire is well worn, the middle third is decent, the inner third is close to perfect.
This is a stock 02 Z28 with koni DA in front and koni SA in rear run on the roadcourse. No doubt that suspension upgrades are needed. I did not upgrade because I want to run SS.
A friend in a prepared TA running 315 rears had the same wear.
My question is: why run anything larger than 275 rear, assuming 275's are in front, if the "contact patch" is not 275. I use quotes because the inner edge of my kuhmo's looked brand new and did not contact anything.
(I ended up flipping the tires on the wheels and using the old rears as practice spares.)
On the rear, the outer third of the tire is well worn, the middle third is decent, the inner third is close to perfect.
This is a stock 02 Z28 with koni DA in front and koni SA in rear run on the roadcourse. No doubt that suspension upgrades are needed. I did not upgrade because I want to run SS.
A friend in a prepared TA running 315 rears had the same wear.
My question is: why run anything larger than 275 rear, assuming 275's are in front, if the "contact patch" is not 275. I use quotes because the inner edge of my kuhmo's looked brand new and did not contact anything.
(I ended up flipping the tires on the wheels and using the old rears as practice spares.)
Forgive me if I'm oversimplifying this but...
Is it because the rears are on a solid axle, thus having little to no negative camber?
You dial in neg camber up front to fight this very issue(tires rolling under). But w a solid axle you cannot dial in camber out back (well, some people bend the axle).
That said, a wider tire should still have a wider contact patch when rolling under. Wider will not eleviate the prob, but could offer more traction.
Is it because the rears are on a solid axle, thus having little to no negative camber?
You dial in neg camber up front to fight this very issue(tires rolling under). But w a solid axle you cannot dial in camber out back (well, some people bend the axle).
That said, a wider tire should still have a wider contact patch when rolling under. Wider will not eleviate the prob, but could offer more traction.
Last edited by subtlez28; Jun 19, 2007 at 10:39 AM.
12 Second Club
Joined: Sep 2005
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From: Bucks County, Pa.
Originally Posted by subtlez28
Forgive me if I'm oversimplifying this but...
Is it because the rears are on a solid axle, thus having little to no negative camber?
You dial in neg camber up front to fight this very issue(tires rolling under). But w a solid axle you cannot dial in camber out back (well, some people bend the axle).
That said, a wider tire should still have a wider contact patch when rolling under. Wider will not eleviate the prob, but could offer more traction.
Is it because the rears are on a solid axle, thus having little to no negative camber?
You dial in neg camber up front to fight this very issue(tires rolling under). But w a solid axle you cannot dial in camber out back (well, some people bend the axle).
That said, a wider tire should still have a wider contact patch when rolling under. Wider will not eleviate the prob, but could offer more traction.
Unless your axle tubes are bent to give static positive camber back there, you will still get more off apex/exit "launch" from a wider tire. Maybe some of the gurus (mitch, Sam, cal, foxxtron, etc.) could chime in here with their opinions/suggestions??
Thread Starter
Teching In
Joined: Jan 2007
Posts: 38
Likes: 1
From: MA
Thanks guys. I was surprised that the inner portion was like new. I wish I had taken taken some pics before I flipped the tires and ran them.
Next event I'll talk to some of the solid axle Ford guys and see if they see the same wear.
Tires are lasting twice as long so thats good I guess.
BTW, I was running between 32 -34 psi cold. The rear does have decent grip (on 710's). The car is sloppy compared to a race setup but is balanced fairly well.
I'm sure controling body roll in the rear would help the situation but only shocks are allowed in SS.
Thanks for the input.
Next event I'll talk to some of the solid axle Ford guys and see if they see the same wear.
Tires are lasting twice as long so thats good I guess.
BTW, I was running between 32 -34 psi cold. The rear does have decent grip (on 710's). The car is sloppy compared to a race setup but is balanced fairly well.
I'm sure controling body roll in the rear would help the situation but only shocks are allowed in SS.
Thanks for the input.
12 Second Club
Joined: Sep 2005
Posts: 4,273
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From: Bucks County, Pa.
Originally Posted by CTSmechanic
You can run camber and toe in a solid axle... I have seem as much as a quarter of toe and over 3 deg of camber you just need a floating rear and crowned axles...
