Directional tire question

[CapriRacer]

Originally Posted by puddleglum

I did that already a while ago to help with the inside edge wear and it has helped. The wear I'm getting now is more that the lugs are getting wedge shaped. It's like toe in wear except the feather edge is radial , not lateral across the tire.

And that sounds like an alignment problem.

[puddleglum]

So, would it still be a toe problem?

[gasstingy]

IMHO, running a directional tire the wrong direction will probably have a negative affect on foul weather driving. My guess {and only a guess} is that the tread pattern is designed to shed water in only one direction. There would be no need for the manufacturer to worry about the other direction because nobody backs up that fast {compared to driving forwards}. Worth investigating, I'd at least contact the tire company and ask what makes them directional.

[fjasper]

From what I understand, camber doesn't make as big a difference as you'd expect on edge wear, that's usually a toe issue, assuming inflation is ok.

If I was you, I'd have a good suspension guy take a close look at the control arm bushings, strut mounts, sway bar links, and any other rubber parts under there, and replace any that don't look good. These are basically wear-out items on a lot of cars these days, and if they're weak, they can allow the suspension to shift pretty dramatically under load. Mine were allowing the wheels to move a couple inches fore/aft under acceleration vs. braking, making it impossible to get the suspension set up right.

Then load the car up to the weight you usually run it and have the alignment checked that way. Just explain to them that you usually drive the car with this load. If they don't want to align it because it's not at the "correct" height, find a better shop. It might be that you need some aftermarket parts to get it to align right under load. Camber bolts or slotted holes, as mentioned above, are pretty straightforward. Or you could up-rate the springs, but that can take some research to find the right ones.

Some suspensions alter toe when they compress, for handling reasons or because of compromises in design. I think VW had a little ad campaign a few years ago pointing out that the rear wheels would toe in when the suspension compressed, supposedly making the car handle better. If this sort of thing is happening, the loaded alignment should find it.

Another (remotely) possible factor is that if the suspension is sufficiently compressed, you might be outside the optimum damping range of the shocks, which can allow some uncontrolled suspension motion. There are shocks that don't have this problem, but they tend to be expensive. Koni Sport yellow shocks are supposed to have linear damping throughout their range of travel.

I've been told that if you run a tire one direction for a long time and then run it the other direction, you run an increased risk of tread separation, but that might be an old wive's tale. I had a tire shed about 20 square inches of tread one time, but it was on a recently purchased used car, so I didn't know the history.

[Joenavy85]

Originally Posted by CapriRacer

First, the source of your problem is mis-alignment.

can't say that for sure, i checked my alignment every time i changed my oil and it was always good, but not rotating my tires caused them to wear more on the front than the rear. the uneven wear he likely meant was front wearing more than the rear. i'm not saying that mis-alignment won't cause uneven wear, it will, but that wear will be uneven across the tire, wearing one side more than the other. without rotation front tires will always wear faster than the rear tires, regardless of alignment.

[CapriRacer]

Just so everyone understands:

Steer tires tend to wear on the shoulders, where drive tires tend to wear in the center.

On Rear Wheel Drive (RWD), these two things occur separately and you can see the difference. The wear rates are about the same, but the pattern is different.

On Front Wheel Drive (FWD), both of those occur on the same axle - the front - while the rear pretty much just tracks behind. Because both of those actions are on the same axle, the wear is even across the face of the tread but the wear rate is substantially higher than the rear. My figures show about 2 1/2 times faster.

The above assumes reasonable toe in and camber values. Needless to say, toe accelerates the wear rate at the end where the excessive toe occurs.

But when there is a lot of camber involved, the amount of toe acts like a multiplier. It not only accelerates the rate of wear, but causes irregular wear to accellerate as well.

Put another way, if you have a vehicle with a lot of toe and little camber, you will get a little irregular wear. If you have a vehicle with a lot of camber and little toe, you will get a little irregular wear, but if you have a vehicle with a lot of camber and a lot of toe, you get irregular wear WAY out of proportion campared to the effect of one or the other individually.

So when you are looking at irregular wear - as per the first post in this thread, he has the classic symptoms of noise and rough riding - we need to look at what the camber values are. The camber values might be spec'd arbitraily high in order to get good handling features - and it does that - but at the expense of tire wear. Add excessive toe, and the problem gets large in a hurry.

[puddleglum]

Well, I have decided to run the rear tires in reverse for a while and see what happens. Having a tire fail because of the reverse direction is a concern, but I'm guessing it won't happen. As for the tread not cleaning properly, I don't think it should be a problem on the back. I know on bicycles and some farm machinery, directional tires are supposed to be mounted in reverse on the non driving wheels. The reasoning is that the ground is pulling the tire and slip force is in the reverse direction. I am suspecting that the alignment must be changing some with load and that I should look at getting a loaded alignment done.

[Galane]

Something you should ask for at an alignment shop is they ensure all the adjustable alignment points match exactly side to side. Some shops just get them inside the specified range and call it good, no matter if one side has positive toe or camber and the other side is a bit negative.

A good shop will always road test a car before and after doing the alignment so the mechanic knows what the car is doing wrong before alignment and whether or not it's right after.

Some FWD cars specify zero toe or some toe out for static alignment because under power the suspension flexes enough to produce toe-in. In such cases worn or deteriorated joints and bushings will result in an incorrect static adjustment and/or too much toe-in under power.

For rear axles of FWD cars there are adjustable, tapered shims available, if the spindles are removable. The back wheels on my 1995 Buick Century were way off until a shop installed shims to bring them to proper alignment.

With non-removable spindles, it's either replacing the axle or getting it bent to twist the spindles back to where they should be. Never use a jack on a torsion beam axle's beam. Always use body jacking points or put the jack under the arms/ends of the axle.

[puddleglum]

I'm going to resurrect this because I finally wore out my noisy, odd wearing set of tires and had the alignment rechecked when I had the new tires installed. This time I had them check it with a 450lb load in the car since that is a pretty average load. Toe and camber were way off, even though they were right on with the car empty. I have to get alignment kits before they can adjust it, but at least I think I have a plan to fix it.

[puddleglum]

I just ran across this tonight looking for something else. I think it's time to give a long term update. I did in fact buy and install the camber bolts and link kits. I had the camber readjusted to spec while it had a 450 lb load. Since then, my uneven wear issues have disappeared. Both my summer and winter tires are wearing evenly across the face of the tires. I haven't noticed a measurable improvement in mileage, but there are too many other variables that would affect that. It's something I would definitely recommend if someone is having a similar problem.