Welcome to the Porsche Turbo experience. Track alignment usually dial in lots of negative camber. Much more than 1 degree of negative camber will increase inner tire edge wear. Camber and toe adjustments move inversely on the rear end. Take out negative camber and you get more toe in resulting in the same problem with worn out inner tire edges. If your car is at stock ride height, get some adjustable toe steer links. That way you can take out negative camber and also adjust out too much toe in. If you're not at stock ride height, you'll adjustable upper links (dog bones) or factory split lower control arms. You'll also need adjustable drop links.

 

Well, I have found toe to be the main driver of uneven rear tire wear on both my cars.

I had the Boxster aligned once and it was returned to me with teh comment the rear camber was at the max allowed and still be within factory sanctioned settings. I was concerned about tire life -- I had the car in for new tires and alignment -- and handling, road feel, and stability. The shop owner assured me the car would be fine with the large amount of rear negative camber.

Frankly I had my doubts but the car felt just fine and tire life was just great. Typically 20K+ miles at the rear and double at the front. Tire wear was even across the tread to.

While my Turbo has never had too much negative camber if there is too much toe rear tire life sucks. I went through a set of brand new rear tires in around 8K miles.

With all the settings correct and the rear toe set for just a bit of toe -- specified range is 0º05' to 0º15' -- rear tire life is 20K miles or more.

And with the toe setting in the above range the car's handling, stability -- up to 165mph at least -- and road feel is just fine.

On the street, with the car driven in a reasonable fashion, inside rear tire wear is an alignment problem and honestly is just a waste of rubber.

Now if one drives the car in such a way that he breaks loose the rear tires often either when taking out from a stop, or upshifting, or when taking a corner, rear tire life of course will suffer greatly and tire tread wear can be uneven. In fact without LSD rear tire wear will be uneven from side to side, with in the USA at least the right rear tire wearing noticably faster than th left rear tire.

 

My car was aligned a bit over 2K miles ago with rear camber sat at -1.20 degrees and rear toe at 0.27 degrees total.

My car is lowered about 1.75" with KW V1 coilovers with less than 2500 miles on them and has upper adjustable dog bones, also an Eibach adjustable rear sway bar.

Here is how my tires are wearing

 

It is normal in cars like Porsche, BMW M and AMGs. Some people like to set the neg camber lower than factory spec to avoid this but could affect the driving in some points

 

LuvPorsche said it. Tarrett rear toe links allows you to correctly set the toe to maximize handling and tire wear. I went through two sets of rears before seeing the light.

Porque

 

I'm nearly certain my car is set up correctly for maximum tire wear and good handling too. I don't need adjustable toe links as I have solid mount adj rear upper dog bones and I can get everything easily within specs desired.

In my above post # 18, what do you find fault with?

Also what is your rear total toe and camber set at where you no longer see the wear you had prior?

TIA

 

Camber will wear the tire gradually inner to outer across the tread. Toe will wear the inner 1-2" or so. Toe is your issue. Your static rear toe setting is correct but it's likely all over the place under load. The rubber bushing in your rear LCAs are likely breaking down and allowing toe to change under load moving fore and aft during braking and acceleration. It's a very common problem on these cars. Install solid TA bushings and inner monoballs and your issues will be all but eliminated. Added NVH is negligible.

 

I lowered mine few months back, 1" and pretty much rear inner tire got bald fast lol, but after getting a good alignment done by a shop that align race cars (race cars) they fixed it, no more tire wear/i'm on winter tires/package atm. - I know they adjusted the toe. and my alig was wayyyyyyyyy off.

 

This.

 

I just did the above what pwderhound said. Still trying to figure out what alignment to run. I run as little as camber as possible, but not sure on toe. Before the mods I ran +.22-.25 per rear tire, so almost +50 total and the tire wear has gotten a lot better. Not sure if I should run that much on the stiff LCAs

 

Cup spec is +17' per side (+34' total toe). That's minutes. Translated to degrees it's +.28º per side or +.56º total. That's what I run and my tire wear is absolutely dead even on all the way to the cords across the whole tread. My suspension is full monoball.. I would not run less than +.50º total in a rear engine 911. Anywhere .50-.56º is good..

These were full tread NT01s at the start...

[url=https://flic.kr/p/AbLpNk]

 

That sure would be nice. I don't have full momoball, but mono on the lca and solid thrust bushings. Hope mine looks like that!

 

it's all about aligning/controlling toe...I run a 'compromised' camber setting that works great/even wear on track but tapers a bit with the many street-use miles (although used 'well' there too ) ...generally about 1mm even difference from outer to inner when 'done'

 

Thanks for your comments guys. As noted in my post #15, the squat under hard acceleration is wearing the tires like this. I agree it's the toe that changes that is causing the wear.

What I don't know, but assume, is that toe in increases during suspension squat as a built in safety device to keep the car pointed in a safe direction. If it was opposite and it towed out or was totally neutral, the car would be difficult to handle.

So, how much of the increase in toe is due to suspension compression and how much is due to rubber bushing deflection in the toe links? In a track car, or one set up for ultimate handling on relatively smooth pavement, high spring rates can be used. This alone will minimize squat, therefore excessive toe in under hard acceleration.

On my car, the KW V1 coilovers are fairly softly sprung and compliant. I'd assume my car with less than 30K original miles has the rubber bushes in the rear toe links still in fairly good shape. I don't track my car and never intend to, so a solution to the rear tire wear issue should be one that will not compromise the road noise or the ride.

I'm thinking of 2 things. First may be a progressive rear shock spring of a higher rate to decrease the sag upon accel a bit and second, to manufacture polyurethane bushes with a steel sleeve to take the place of rubber in the OE links.

I don't need to spend hundreds of dollars for something I can easily make myself. I don't need the adjustable length feature either, or the tapered pin that could be bushed to decrease or eliminate bump steer as that's not an issue.

I'd appreciate any info on how much of the toe change during accelerating squat is due to link OE bushing deflection and how much to rear spring compression. I have a feeling just doing the bushings alone won't make a huge difference.

I'm here to learn:-)

 

too much toe in IS the issue. everyone that has ever gotten one of these and gone thru a cpl/few sets of rears on a lowered car deals with it. the excessive inner wear.

you simply need adjustable to links whether tarett/torque solutions, whatever. adjustable, to dial out less toe IN, and compensate for had acceleration squat which also places excess demand on the inner tread section.

all too common. adjustable toe links is the cure to uneven wear, coupled with a properly aligned and inflated set of rears. have just and only one facet of this equation out of synch? buy new tires. ( again )