Tire direction/rotation - a"This" vs. "That" question
 

You may remember me from such memorable threads such as this weeks "My wifes car has no spare tire and we got a flat and I'm pi$$'d" thread. Today's topic continues on that, but brings up a question of tire rotation.

I understands "This":


http://forums.pelicanparts.com/uploa...1488479039.JPG

There is an arrow which tells you which way the tire spins. One would assume you could rotate this tire between the left front and rear of the car, but wouldn't put it on the right side of the car where it would spin in reverse, unless one wanted to take the time to remount the left tire on a right side rim so the arrow would still spin the right way.

Now "That":


http://forums.pelicanparts.com/uploa...1488479240.JPG

Here the tire simply says "outside"

In this case, does direction matter? For example, with this tire, one could theoretically switch it to all four corners of the car and the "outside" would still be outside, although the tire itself would spin in a different direction on the other side of the car.

So that brings up my wife's flat tire from earlier in the week. I removed the tire and found out why the fix a flat didn't work.

http://forums.pelicanparts.com/uploa...1488479593.JPG

She must have one hell of an alignment/ and or suspension problem, and that will need to be addressed. The other front tire had the same extreme wear on the inside edge. Both will have to be replaced. The rear tires also had some wear on the inside edge, however, not as bad, and have a LOT of good treat left.

Ideally, I'd like to get new front tires/ address alignment issues, and then keep rear tires but have them swapped between rims so the inner wear would be on the outer side which has no wear at all, but doing so would mean the "outside" would be on the inside of the rim, although the tire would effectively be spinning in the same direction. I can see the tire shops already saying "no" ...

Basically, it boils down to the $500 question of do I buy new rear tires- but the "arrow" vs. the "outside" directional thing is something I have always wondered about.

Thoughts?

Some tires have a different compound on the outside vs the middle or inner tread.

Odd, the shoulder tread pattern on the one that says Outside would make me think it's uni directional. The middle tread not so much.

That's one hell of a camber / alignment issue she's got going on there, middle of the tire looks to have tons of meat still on it.

If the tire has the directional arrow, then you rotate only front tires to back. If it simply says "outside", then you can rotate in a crossing pattern. Right front to left rear, etc.

I agree that you should have alignment checked.

Yea, you have a real bad alignment problem. The car has to pull to one side or the other or have some sign of an issue.

That is tire abuse!

Your wife is a tire abuser!!!!

I asked her if she has been attending any ricer events, but she's claiming "no"


http://forums.pelicanparts.com/uploa...1488482403.jpg

It really got me wondering about the science behind the directional thing. I had always assumed the steel belting was altered in directional tires to only be intended to spin one way, and that reversing it would lead to world destruction and bad things.

The rear tires really do have a lot of meat left, without the inner wear issues. Weirdly, I looked at the tread on that car from time to time, and it sits so low I just saw the middle "good" tread and never noticed the inner wear. It never pulled either. Only lately did I notice feedback throught\ the steering, which felt like a missing wheel weight, but no pulling.

Too much toe-in can cause scrubbing on the outside of the tire like that. Most tires don't have negative camber that could cause the same wear.

I was thinking a toe problem myself. Nothing seems loose in the joints, but I am just pulling on the rotors by hand. I don't think tire pressures were too far off either.

As I was reading this thread, the question arose, "were those tires ever rotated?" With that extreme wear on the inside of the fronts and only very slight wear on the inside of the rears, why wasn't that wear pattern noticed before the tire failure?

It's not entirely clear from the first post if both front tires had the wear on the inside. If so, then negative camber or toe-out would be the likely issue. It will be interesting to hear what the cause turns out to be.

Asymmetric tread design is normally for wet weather, tire noise, cornering benefit on cars with negative camber.

https://www.kaltire.com/wp-content/u...ead-design.jpg

https://www.kaltire.com/whats-difference-directional-asymmetrical-symmetrical-tread-patterns/

By chance is your wife's car a Mercedes?

A lot of Mercedes love to wear out the inner edge of the front tires due to a decent amount of negative camber and positive caster. The cars steer and handle great, at the expense of tire wear.

A random example of Mercedes front tire wear:
http://www.benzworld.org/forums/atta...-25-33_285.jpg

^It's a volvo v60, but it has 19 wheels and a "sport" type package. I was concerned that it was a setup like the mercedes as well. I've never stuck the Cambermeister thingee on them, but I am going to. I am having new tires placed now. Next week, the car will go into the shop for alignment. One of the things I want to find out is just that- is this a problem because my wife hit a ditch a while back? or a factory setup issue? I want to get to the bottom of what caused it.

Also- (answering some of the earlier post) the wear was on inside on both fronts. The tires were rotated early on in the car. At that point, the inner wear (on what are now the rear tires) was not to the point it was noteworthy. Looking at the rear tires now (in hindsight), yes, the wear was occurring, but it did not have the chance to do as much damage before they were switched. If I could insure those rear tires were NOT getting continued excess wear on the inside (such as neg camber), they would still have plenty of life left. That was my original goal in asking about rotating the rear tires in the back with the "outside" emblem- from left rear rim to right rear rim, so the inner worn section would now be on the outside, and the inside could wear down the meaty outer sections of the tires- if the car had some neg camber bias dialed into the suspension setup. In my understanding, there would be no technical reason why it couldn't be done, other than tire shop being scared of legal liability. They tread pattern is more or less symmetrical.

That's a longwinded response, but I will get back on the cause mid- late next week when it goes into the shop. thanks as always for repsonses.

Do you know what the factory alignment specs are?

On my Mercedes I replaced the front rubber bushings, reduced the camber from -1.8 to -1.3, and added 3 lbs of air to the tire inflation pressure and the situation became much better.

Simply adding 3lbs of air pressure made a reasonable difference in wear before doing the above work.

Good luck! It's a real bummer to have to replace expensive tires due to extreme wear patterns.

I've heard it bandied about that negative camber doesn't cause the crazy inside tire wear as much as too much toe in does.