Wheel alignment

pcar928fan;14473 wrote: If you are running the inside edge of the tire much more than the rest of the tire how in the world could you POSSIBLY wear the rest of the tire at the same rate??? Just think about that for a minute. I'll wait for you...



Rick, just look at a race car running a ton of camber, the outside edge (other than from cornering) will be untouched while the inside edge will be GONE. Just a fact of life. Run ZERO camber if you want to try and wear them evenly and then don't corner to fast or you will then wear the OUTSIDE edge more. On the wheels that steer the car it is impossible to get good handling and even tire wear across the width of the tread. For a brief period there were tires with built in camber... Pretty cool! I bet those wore evenly...

Your car should be rock solid and smooth at 150+ let alone 80. But it is not always (perhaps not even usually) an alignment issue when you get the shakes. It is probably and out of balance wheel...could be that it was put out of balance by a poor alignment though. The thing that you are really looking for is left and right side wearing the same way at the same rate. You also want the inner edge that is wearing to be wearing smoothing and not have any scallops or dips in it. I bet if you were to just change out the tires for new tires (properly road force balanced) that your shakes would go away.

All speculation at this point since I have not driven your car or seen your tires... Report back with more info when you get a chance to try new tires or get an alignment (I'd start with the tires though!)

Thanks James. All of what you posted makes sense. I do have even wear on both front tires. Smooth on the inside tracks for both and no scalloping. I am in the process of 4 new tires and they should be on soon.

After the new tires and balancing I will report back.

Thanks for everyone's advice and help!

Yes, excessive camber will wear the inside edges.

So will toe-out. Lifting the car before or during alignment will always result in toe-out.

You can check this quickly and easily.
1) Get two long straight things. Boards, pipes, etc.
2) Get two helpers and a tape measure.
3) Pull the car forward with the wheels straight ahead and stop it with the parking brake.
4) Have each helper hold a straight edge against a front wheel, as high as possible without touching the body, pointing forward and level.
5) Measure the distance between the straight edges just forward of the car, and as far from the car as possible.

The straight edges should be slightly closer together at the far ends. If the far ends are farther apart, you have toe-out, and the car needs a good four-wheel alignment.

Thanks Wally.

Well, I went ahead and had an alignment done at a local Firestone. They have a Hunter Alignment system. Even with all the advice here, I went and scheduled the alignment for this morning. I talked to the manager a couple times about not lifting the car and letting the wheels hang before the alignment (and why).

While sitting in the waiting area I could hear the rumble of my car being pulled into the shop. So of course I wanted to watch. I was amazed as I watched one of the mechanics pulled my car into the non alignment bay. I asked the manager what they were doing with it there? "They are going to lift it to check it over before the alignment". WTF! So, I explained again, why they can't and had him read one of the RL alignment guides I printed out. "Why 928 suspension is different than other cars 4/16/03" - Maybe written by Wally?

After they opened the hood to ogle the engine and comment how nice the car and engine was, they took it to the Hunter bay and didn't lift it.

Here's the results before and after alignment.


I'll be getting the new tires (Bridgestone Potenza RE-11's) sometime next week. I'll try the high speed test then.

I disagree when you say camber will cause tire ware.
Toe wares tires.

Think of how the wheel look on the back of a Volkswagen beetle, yet the tires ware even.
Camber, neg or pos will be hard on the side wall but you should still have all the tire on the road.
As you accelerate the force increases toe out, so if you set it to zero when standing still it will toe out and scrub the inside of the tires at 60 mph.

I must have 7 or 8 deg camber on the front with no tire ware.
This not totally what I wanted, and I am going to correct it, but it is because Carls tubular upper control arms are shorter then stock.

Yep. Looks like my Toe (and some Camber and Castor) was out causing my ware.

Brad, I hate to break it to you but there is NO 928 suspension that will allow -6 Deg of camber! NONE! Nada, ZIP...unless you are running something custom the MOST you can get out of an S4 is about -2.4 deg. If you change to earlier suspension arms (upper or lower, I can't remember which) you can get just over -3 deg... Nothing even CLOSE to 6.

Your physics in Canada must be different than our down here in the States because if you push really hard on one side of a tire and hardly at all on the other side of the tire, the side being pushed down, WILL wear more. If you add some toe then it is even worse of course.