Trying to understand tire wear pattern.

cooltoy

I am currently putting new tires on my Z.


When I took off my old ones, I notices that on both fronts and rears most of the wear was on the inside edge.


I having trouble understanding why that would happen. I am at stock height with wider tires. I would not have thought that putting wider tires and gong from with a larger rim diameter would have such an effect.


I did not think that I would have needed toe adjustments if the car was not lowered.



I went from stock 19s to 245-35-20 and 285-30-20.

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Rusty

How many miles are on the tires, and what are your alignment settings?

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Trips

Typically center tire wear signals over inflated tires



Bald tires signal STOP DOING DONUTS!!

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cooltoy

28,000 km.


I never had an alignment done. I just assumed new car, new tires.

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cooltoy

Is the first image of the driver side, or the passenger side?

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Rusty

Just over 17,000 miles. What tires are on the Z?

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cooltoy

Pss.

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danegrey

I would say alignment, might be the problem...
been back and forth on different alignments and it was always the alignment for me...

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cooltoy

OK. I'll have to get that done with the new set.


With this last set I did not think it was necessary, since I went from new stock set to the new 20 inch set.


I guess, I was wrong.


Thank you.


So, was the inner edge dragging, thus the wear in that area?

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Rusty

The inner edge of my tires wear faster than the rest of the tire. The more camber you have. The faster the inner edge wears.

My alignment spec's are.
Front;
Camber 2.2.
Caster 6.5
Toe 1/16" in.

Rear;
Camber 1.8
Toe 1/16" in.

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SeeThruHead

Could be either side depending on which toe issue you have.

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cooltoy

So changing to a wider tire from stock changed my camber? Or is it that way from the factory and if I kept my stock rims, the same wear pattern would have happened?

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filip00

Couple of things to unpack here. Regardless of what other will tell you, ride height doesn't matter. If you had adjustable suspension, you could have same settings on camber/toe regardless of how high or low you go with the suspension. Yes, there will be a bit of difference in the damping and how the wheels will move, but it will not impact the tyre use that much. If you just lower the car and don't adjust the suspension, then often you add some negative camber, but like I said - if the suspension is fully adjustable, then you could get practically the same values everywhere regardless of your ride height.

With that out of the way, let's analyze what you said. Inner edge is worn? That means the tyre is resting on it more than on the rest of the patch, meaning you've got negative camber. Not a problem, but that's the price you pay for negative camber. You can however, "fix it", by adding a toe-in, so that the tyre would "roll itself out" while driving, so that you'll be using more of the patch.

In short - yes, go get wheel alignment, they'll help you out there and explain further if necessary.

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cooltoy

OK. I understand that now. Thank you.


I guess what I am trying to understand is why it occurred? The only difference between now and when I bought the car is the rim diameter and wider tires. Is that the reason for the negative camber?

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Tractionless

I'm at OE ride height on all OE suspension and set my rear camber to 1.0*, still wore the inside edge of the passenger side tire more, drivers was perfectly worn all the way across. Toe in spec. and front is double the rear as suggested on this forum.

Keep in mind as you load weight into the car (including sitting in it to drive) negative camber increases and is why you can request to sit in the car at some shops. If not, as soon as you get in all the values you were given from the machine change a good deal and forget loading it down for a road trip!

Secondly, when you accelerate hard the camber changes more negative AND therefore you actually LOSE contact patch (and straight line traction) due to forces being applied to the inner portion of the tire and lifted from the outer.

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