Tire Wear?
03-15-2015, 02:51 PM
#16
Race Director
Toe out will eat tires pretty quickly, and rear toe out makes the car handle really dangerously, too. Keep the camber and realign for a little toe in, which is fine. Since this is just for street use, Porsche spec alignment and camber should be fine.
And if you're not at least occasionally driving this car like a sports car, tsk tsk on you, you might as well have bought a mercedes or jaguar or something.
And if you're not at least occasionally driving this car like a sports car, tsk tsk on you, you might as well have bought a mercedes or jaguar or something.
Toe in means the tires swing in even more and the toe in becomes even more excessive.
03-15-2015, 02:57 PM
#17
Bruce,
Yup, The camber setting was my original thought for my tire wear. Mine was exactly as yours.... the inner rears were worn to the canvas.
No expert here, but camber and toe make some logical sense to me for that type of wear.
Hope to find a knowledgeable experienced local guy to solve the problem. At the very least I have some reference from all you list members. Thanks!
KV
Yup, The camber setting was my original thought for my tire wear. Mine was exactly as yours.... the inner rears were worn to the canvas.
No expert here, but camber and toe make some logical sense to me for that type of wear.
Hope to find a knowledgeable experienced local guy to solve the problem. At the very least I have some reference from all you list members. Thanks!
KV
So now ...
As a DD up and down the freeway I set my tire pressure at the rear to 44 cold. This pushes the tread at the center down and reduces pressure on the inside. But on the fun roads the tires bounce off the pavement and the car skitters. So I drop the rears to 37 cold for those roads.
This is still experimental, but with 5K on new tires things seem to be working. It is a bit of a pain, but life offers compromises, and changing air pressure seems to be better than changing tires.
Oh, and I did slightly reduce the rear toe. And I confess to a couple of driving style changes as my fun driving now involves only Sport Plus and manual shift control of the PDK. So I am dealing with multiple variables.
YMMV!
03-15-2015, 02:59 PM
#18
Race Director
I suspect along with the less camber the toe was changed and it was the toe that resulted in the reduction in tire wear.
I get to follow Porsches down the road once in a while and under way the rear tires loose their camber and the tires become as near as I can tell vertical.
As I have mentioned before the alignment settings are settings that are applied and measured and in effect with the car stationary. What the settings become when the car is actually underway is something else.
I hate to keep beating this subject to death but too many Porsche owners accept horrible tire life with uneven -- and potentially dangerous -- rear tire wear as the norm for these cars but it is not the norm.
For street driving one can have a good handling, a car with the road feel we all love and enjoy, with good rear tire life, with good even tire wear.
All it takes is the proper alignment.
I get to follow Porsches down the road once in a while and under way the rear tires loose their camber and the tires become as near as I can tell vertical.
As I have mentioned before the alignment settings are settings that are applied and measured and in effect with the car stationary. What the settings become when the car is actually underway is something else.
I hate to keep beating this subject to death but too many Porsche owners accept horrible tire life with uneven -- and potentially dangerous -- rear tire wear as the norm for these cars but it is not the norm.
For street driving one can have a good handling, a car with the road feel we all love and enjoy, with good rear tire life, with good even tire wear.
All it takes is the proper alignment.
03-15-2015, 05:12 PM
#19
Drifting
My opinion differs from those who point to rear toe as the wear culprit (absolutely improper toe will wear tires). For me, it was the camber. I wore out my rears really fast but only on the inside all the way down to the cords.... I had no idea as the rest of the tread looked darn good (my first 911).
I had an alignment done and took out much of the negative camber in the rears and my winter and summer tires are experiencing perfect, even wear. The toe was within spec before my alignment. My rear camber is just outside of spec now.
Notice how our cars sit with obviously canted rear wheels (tops in, bottoms out). Now in your mind (and I have an active one), make the tires five feet wide. Where is the wear going to occur? Our rear tires are already really wide.
I had an alignment done and took out much of the negative camber in the rears and my winter and summer tires are experiencing perfect, even wear. The toe was within spec before my alignment. My rear camber is just outside of spec now.
Notice how our cars sit with obviously canted rear wheels (tops in, bottoms out). Now in your mind (and I have an active one), make the tires five feet wide. Where is the wear going to occur? Our rear tires are already really wide.
The combination of high camber and toe in is well known to cause highly accelerated inner tire wear. This happened to me once on the fronts- because I had done an DIY alignment with as much camber as I could get and a little toe out for crisper turn-in. Corded the inside corner in 3000 miles. Realigned for neutral toe after that, still with as much negative camber as I could get, but never had another problem.
Regarding poorer handling... I am not so sure about this. Remember that car companies tweak their suspensions for performance but also safety. When I did my rears, I also had them put more negative camber in the front. The car went from boringly stable to a bit lively.... not twitchy, but more like my 2000 Boxster was from the factory. I am very happy with this change as I was a bit disappointed with my 2009 C2S's handling being pretty darn Buick like. Talk to those who track their cars and one of the quickest things they learn is to tweak the alignment. The reasons are many, but there is no perfect alignment for a Porsche. We love to think our cars are the top of performance from the factory tweaked by engineers who are monks on the weekends and only use special wrenches.... yadda yadda... but the engineers, with the marketing department, come up with a compromise that balances performance (twitchy track like), comfort (stable straight on the highway), and safety (a bit of understeer) as it is best for their target market. And note that Porsche has expanded their eyes on a broader market than just the performance-oriented enthusiast. Remember how even today, the car reviewers talk about the dangers of a rear engined Porsche? Do you think Porsche wants to give any fodder to this line of dialog?
YMMV.... this is just my opinion.
Peace
Bruce in Philly
YMMV.... this is just my opinion.
Peace
Bruce in Philly
I used to curse understeer until I had a car that tended towards oversteer. Gave me a bit more appreciation for slightly balanced towards understeer
I think you have it backwards. A little toe out at the rear is required as when the car is moving down the road under power the rear tires tend to move forward and the toe out becomes nil.
Toe in means the tires swing in even more and the toe in becomes even more excessive.
Toe in means the tires swing in even more and the toe in becomes even more excessive.
Street alignment is slight toe-in both front and rear for stability and tire wear.
03-15-2015, 07:14 PM
#20
Rennlist Member
I suspect along with the less camber the toe was changed and it was the toe that resulted in the reduction in tire wear.
I get to follow Porsches down the road once in a while and under way the rear tires loose their camber and the tires become as near as I can tell vertical.
As I have mentioned before the alignment settings are settings that are applied and measured and in effect with the car stationary. What the settings become when the car is actually underway is something else.
I hate to keep beating this subject to death but too many Porsche owners accept horrible tire life with uneven -- and potentially dangerous -- rear tire wear as the norm for these cars but it is not the norm.
For street driving one can have a good handling, a car with the road feel we all love and enjoy, with good rear tire life, with good even tire wear.
All it takes is the proper alignment.
I get to follow Porsches down the road once in a while and under way the rear tires loose their camber and the tires become as near as I can tell vertical.
As I have mentioned before the alignment settings are settings that are applied and measured and in effect with the car stationary. What the settings become when the car is actually underway is something else.
I hate to keep beating this subject to death but too many Porsche owners accept horrible tire life with uneven -- and potentially dangerous -- rear tire wear as the norm for these cars but it is not the norm.
For street driving one can have a good handling, a car with the road feel we all love and enjoy, with good rear tire life, with good even tire wear.
All it takes is the proper alignment.