What's with my tires ??

pcb

The Diagram Dude
:
2002 MP5
I put my summer tires back on but noticed that two of them had weird tread wear.
I forget whether the two came off the front or rear of the car when I took them off last fall.

Could a bad alignment cause this ?? I would expect scrubbing type marks.
This looks like the tire is rotting/decaying/getting old but why not all the tires ?



Two of them are smooth.



My winter set came off and all the tires looked the same.
 
That's feathering/chopping. Toe adjustment being out of whack *can* cause it, but generally it is caused simply by not rotating the tires frequently enough.

The feathered ones came from your front. Rear tires won't do that unless the toe set is WAY off and you would know if that was the case...

Put the feathered ones on the rear and they will smooth out somewhat... but generally once they start to do this on a directional tire there is no bringing them back to perfectly smooth again. It shouldn't cause a vibration or anything, just make more road noise.
 
Whenever I change out my tires, I just put the pair with the most tread on the front.

I may check my rear alignment again.
I punched through my frame with my t-stands near where the trailing arms connect then had a plate welded to it to strengthen it up. That process may have thrown off my alignment.

The four tires were very close to each other as far as tread depth goes so I can't be scrubbing too bad. But luckily I put the feathered ones on the rear.

I may just ignore it,... I'm sure my two sets of tires will out last my car.
 
I seriously doubt anything is wrong with your alignment. It is "normal wear" for tires.

As you drive on the road, roads have crown. You adjust the steering wheel (albeit very slightly) to compensate for this crown. This creates a slight bit of scrub. When you go around a turn there is a little bit of scrubbing that occurs on the tires. As your suspension flexes over bumps/humps/the bouncy stuff on bridges from the seams/etc, or when you go around a turn and the car leans, it changes the camber (again albeit very slightly) and the tire will scrub a little. Over the course of 5000, 10,000, 15,000 miles this little bit of scrubbing adds up.

Generally, the feathering like that is caused just by not rotating your tires. Regular tire rotations promote longer tire life and more even wear for this reason. more even wear across the individual tire, as well as even wear between all of the individual tires. All cars do it.


With non-directional tires I always use a "modified X" rotation pattern... I will bring the rear tires straight forward. Then switch RIGHT and LEFT tires when they go to the back. This REALLY helps a lot to "even out" the feathering that occurs much better. But with directional tires, it's not really an option.

I wouldn't worry about it. Like i said, with street tires it seldom if ever will cause a vibration issue. Mostly the tires just get noisy. Our cars are noisy as hell anyways so it's not hurting anything lol. With mud tires on trucks however, the tire tread and lugs are much deeper and definitely can cause a vibration. Once they get bad enough it's almost unbearable to drive and the tires are trashed.
 
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I seriously doubt anything is wrong with your alignment. It is "normal wear" for tires...

I wouldn't worry about it...

OK. I'm gonna ignore it.
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It's a pain to check my alignment anyway and I'm too cheap to take it into get it checked.
 
The tire in the top pic looks like it had an alignment issue. It looks to me like the left side of the pic's tread is more worn than the right side, which usually meas the camber was off.
 
I forgot that replaced my rear struts too...

That could have led to an alignment issue as well.

I'm gonna check my rear alignment..

This is my homemade alignment tool.

 
That's some high tech s*** right there!
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Yup...
I lifted the rear end up and spun the wheels to draw a line down the middle of the tread with a marker.

Then set the car back down and measured with my Specialty Shop Tool.

And found that my alignment was dead on... It was about 1-2 mm of toe in.

My SST doesn't however measure caster or camber.
 
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