Tire wear question

jinglevo · Post by **jinglevo** » 14 May 2012, 18:01

I have a tire wear question. Four months and ~3500 miles ago, I replaced a set of worn tires on my '95 850. At the same time, I had an alignment done. The mechanic who did the alignment commented that I would probably be fighting tire wear because my struts were due for replacement. This is not surprising, as the car is still on the original struts, and it has ~190k miles on it.

Now, ~3500 miles later, I am already noticing some irregular tire wear. What I am not sure is (1) what this particular type of tire wear is called (it's not on any of the tire-store wear charts that I've looked at) and (2) whether it is of a type that is indeed likely to be related to worn struts. For an illustration of the wear, see the attached file. This pattern of wear is evident on the outside of the front tires, and not elsewhere. So far, it is not really visible, but I can definitely feel it when running my finger over the tread. Also, this is the same type of wear that the old set of tires experienced, but by the time I replaced them it was much worse.

Many thanks,
jinglevo

sit22II · Post by **sit22II** » 14 May 2012, 21:15

Yea it looks like bad struts

Post by **MoVolvos** » 14 May 2012, 22:44

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What you are trying to describe looks like a Toe or Camber adjustment Issues. Bad struts will usually give you some cupping wear along with some feathering depending on how bad the Strut is. Feathering will also be caused by hard cornering but will be less for the rear than the front tires.

How is your rear tires compared to the fronts? If it is only feathering without cupping I would say it is most likely the Toe or Camber as most Alignment guys will not adjust the Camber on a Volvo as they think it is a NON-Adjustable parameter. Call him and ask! If you can attach a print out of you last Alignment Spec Sheet I can be more precise with the answer.

http://www.strouhaltire.com/tirefaq_align.aspx

Blessings,
BKM
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jinglevo · Post by **jinglevo** » 15 May 2012, 01:33

Thanks. So far the new rear tires are okay, but I definitely saw the same wear pattern on the rear tires on the old set, just not nearly as badly as on the front. I will have to see if I can get a copy of the alignment output.

So what is the name for the wear pattern I am describing? From the description you linked to, feathering should be noticeable when running one's hand side to side across the tread. My tires are smooth when I do that. When I notice the uneven wear is when I run my hand around the circumferance of the tires, but only on the outside edge.

I should have explained the illustration I posted: Not sure what the proper terms are here, but to be clear, the tread is made up of a number of "teeth" about 1" square, each of which is made up of several smaller "toothlets." In my illustration, you are looking at two individual teeth from the side of the tire, i.e. crouched down next to the hubcap looking straight into the wheel well. The unevenness is felt from toothlet to toothlet when I run my hand front to back across the surface of each tooth. It is not felt from side to side. Does that make sense?

Post by **MoVolvos** » 15 May 2012, 01:50

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The pattern is called Feathering and sounds like a combination of very slight Toe In or Positive Camber combined perhaps with driving style. Positive Camber can also cause outer tire wear. Unfortunately in the real world tire wear is a combination of problems unless one issue is out of the ordinary. For yours it could be: Positive Camber, Toe In, Tire Inflation, Driving Style (Swift to Hard Cornering) or the Combination of those. Your Struts maybe worn but is not dramatically affecting tire wear from your description. The only other item that can cause your wear pattern is a slightly bent strut assembly and the SAI Spec on the Alignment would indicate this. I'll look for your Spec Sheet.

Blessings,
BKM
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