Uneven tire wear

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WA1DH
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Uneven tire wear

Post by WA1DH »

I'm trying to diagnose a problem I've been having with front tire wear. I don't know if it's the alignment, tie rods, or the fact that I slightly overinflate my tires.

I drive about 500 highway miles a week (~70-75 mph) and overinflate the tires to 40 psi versus the rated 35. I've read that this helps lower rolling resistance and is better for gas mileage. I don't think this is causing the problem because the wear is on the outside edges of the front tires, whereas overinflation wear is usually at the center. I just had the car jacked up and tried moving the tires side-side/up-down to check the tie rods and ball joints, and I didn't notice anything unusual. If there is any play, it must be very slight.

Here are some pictures of the tires. As you can see, the outer edges are wearing faster than the inner edges and center. Let me know what you think:
http://www.photos.douglasharrington.com/v/tires/
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Re: Uneven tire wear

Post by watkins »

Thats either a camber issue, or your toe is set with both tires pointing slightly in. To really tell, you need to check for feathering.
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Re: Uneven tire wear

Post by AHTOXA »

Right. Toe-in will cause that kind of wear along with feathering on the outside of the tire where most wear occurs.

Time for an alignment in either case.
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Re: Uneven tire wear

Post by theholycow »

Severe overinflation would cause center wear. Your slightly increased inflation barely even qualifies as overinflated unless your tires are rated for a maximum of 35 (rather than your car's recommended pressure).

I agree with the others. Your wear looks like common toe-in. Get it aligned. You could band-aid it by using more inflation but I don't recommend it.
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Re: Uneven tire wear

Post by WA1DH »

I'm kind of baffled, as the wear has gotten worse, the car has now failed state inspection for worn tires, and everyone says its toe in. However, I checked the alignment, and I'm coming up with too much toe OUT. I ran a string parallel to each side of the vehicle (using the door frames as reference points) and here were my results:

"F" and "R" denote the front and rear of the tire in relation to the car (ie. F=closer to front of car and R=closer to rear). Measurements are distance from the string running parallel to the frame.

Driver Side
Front Tire:
F - 3.75" (3 3/4")
R - 4.00"
Toe OUT 0.75" (1/4")

Rear Tire:
F - 3.875" (3 14/16")
R - 3.8125" (3 13/16")
Toe IN 0.0625" (1/16")


Passenger Side
Front Tire:
F - 4.375" (4 3/8")
R - 4.50" (4 1/2")
Toe OUT 0.125" (1/8")

Rear Tire:
F - 4.5625" (4 9/16")
R - 4.50" (4 1/2")
Toe IN 0.0625" (1/16")

As you can see, the rear tires have a toe in of 1/16". However, the front tires are toed OUT 1/4" on the driver side and 1/8" on the passenger side. I haven't been able to check camber yet as I would need to figure out how to make some kind of tool to do that.

A few other clues/symptoms: I've had a clunking from the front right wheel on hard left turns (ball joint?), and the steering wheel vibrates at/over 75 mph.

Any idea as to what parts I should be replacing before I align it and buy new tires? Also, should I set the alignment before or after I put new tires on?

Thanks.
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Re: Uneven tire wear

Post by theholycow »

Your method for checking alignment assumes that the side of your car is perfectly straight. I doubt it.

Use a tape measure on the tire treads. Measure from one tire to the other at the front of the tire and about 180 degrees from there at the rear of the tire. Be sure to measure on the same circumferential groove, obviously.
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Re: Uneven tire wear

Post by comingbackdown »

WA1DH wrote:I've had a clunking from the front right wheel on hard left turns (ball joint?)
FWD? CV joint.
WA1DH wrote:and the steering wheel vibrates at/over 75 mph.
And you're going 75 mph when your tires are wearing oddly WHY?

Multiple possible causes for that one.
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Re: Uneven tire wear

Post by WA1DH »

It doesn't sound like a CV joint. CV joints click - this is more of a clunk-clunk-clunk noise as the weight of the car shifts from one side to the other during the turn.

As for the speed - that's just how fast the traffic moves here. Can't really go much slower than that. I also have an hour plus commute and drive around 600 miles/wk which probably hasn't helped any.

I will give the tape measure method a try tomorrow and post the results.
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Re: Uneven tire wear

Post by WA1DH »

I tried the suggested tape measure method and created a diagram with the results. I also took some new pictures of the tires.

Everything is here: http://www.photos.douglasharrington.com ... /04-27-10/

If I'm calculating this properly, it appears that the results are 1/8" toe IN on the rears, and 9/16" toe OUT on the fronts.

I also took a comparison picture of a rear tire. It looks like the front inside and outside edges are wearing, although the outside edge is going faster than the inner. Everything but the center seems to be wearing :roll:
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Re: Uneven tire wear

Post by theholycow »

Check your camber. I'm not sure how, can't get a tape measure in there. Maybe find a nice very flat piece of concrete (not asphalt) to park on and use a carpenter's framing square. Google may say a better way.

Otherwise, I'd guess that you like to take turns fast and need to compensate by overinflating (scares some people) or aligning with some negative camber (looks ricey).
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Re: Uneven tire wear

Post by AHTOXA »

Lift one front tire in the air and wiggle it left to right. Watch for excessive play. This could very well be TRE issue.
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Re: Uneven tire wear

Post by WA1DH »

Ok, I've looked up a few how-to guides for measuring camber with a level and digital caliper (both of which I happen to have). I'll give that a shot tomorrow.

It can't be my cornering, as most of my driving is highway and the few corners I do take are at slow speeds. I've jacked it up and checked for play before but I will try again now, maybe if something is worn it will have gotten bad enough to be noticeable now.

Thanks for the help.
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Re: Uneven tire wear

Post by kamesama980 »

Have you gotten it fixed? what was it? no pics.

If not, take it to a shop that will inspect for free and ask for them to show you what they find while it's on the lift. You may have to look around but there are some that do that. usually small-mid size semi-untrained places more interested in throughput. NTB, Pepboys etc. just call around and ask. say you have uneven tire wear and ask how much to have JUST an inspection and estimate.
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Re: Uneven tire wear

Post by WA1DH »

Well the toe was way off in the front. I also had a bad front right ball joint - it just flopped from side-side in my hand when I got it out. I suspected the tie rod ends could be going too so I replaced those. So, 2 new ball joints, 2 new tie rod ends, 4 new tires, and a DIY alignment and so far so good.
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Re: Uneven tire wear

Post by potownrob »

success!!
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