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Abnormal tire wear for which I can't find an example on the internet

Dear Tom and Ray,
I have a 2008 ML350 Mercedes SUV. On each set of tires, the OEM tires and a replacement Continental DTS series, I have seen uneven wear on all four tires. Basically, when you run your hand around the tire (not across the width of the tire, but around the circumference) you can feel that the tread is higher on one side of one of the tread cubes then the other. When you run your hand in the other direction, you cannot feel the edges. I have had the tires aligned with the new replacement set of tires and the inflation has been according to the information on the cars sticker. They have also been rotated front to back as they are asymmetrical.

What do you think is causing this wear? I am about to buy new tires.


I have Continental tires on my bicycle and they are by far the best bike tires I’ve ever had.
Long wearing, great grip and about 1 flat every 2 years riding to work each day on dirty city streets.
Tried another brand tire with kevlar belts and I got a flat every 2 months.

I have Continental (OEM) tires on my car and they are the worst tires I’ve ever had.
Uneven wear on the extreme edge and noisy.
I had to get them flipped on the rims before the edges wore out.

First off…

Tom and Ray don’t post here. You just have us…some are seasoned mechanics…others are just car enthusiasts.

Who did the alignment??? This sounds like an alignment problem.

I too had serious problems with Contis. In my case it was on a Toyota pickup.

This sounds to me like it might be “scrubbing”, a condition caused by poor toe-in. I’m with Mike, this needs to be looked at by a good chassis shop and the alignment checked.

Uneven tire wear like you are noticing might be nothing to worry about. If you take a tire tread depth gauge to several cars, you can find that most tires don’t wear evenly around the tire. I’ve seen it on cars, semis, and motorcycles. However, it might indicate the tires are out of balance. The important thing to consider is that when measuring tread depth to determine whether tires need to be replaced, be sure you measure the most shallow part of the tread.

Something else can explain this type of wear. Do you turn the steering wheel a lot while the car isn’t moving? This can cause uneven wear.

Its a sawtooth pattern, I’ve seen it on vehicles and on charts in tire shops. Unless its real bad, I don’t think there is much you can do about it. It seems to occur on tires that have a aggressive block tread for off road use.

If you had included a side to side in your rotation, you wouldn’t see this problem. You can do a side to side on asymmetrical tread tires. You didn’t mean unidirectional did you, those can only go front to back.

Its called cupping, or scolloping. It can be caused by very many things. Warn out suspension peices, bad struts, or even driving habits like agressive braking. It actually has been covered by Tom and Ray before. And it is also a real problem with motorcycle tires.

AWD SUV’s driven at 80mph on dry pavement will make ANY block-tread tire wear unevenly…It’s the impact of the leading edge of the block followed by the scrubbing action as the trailing edge lifts off the pavement…If you X rotate them, it will even out even though current tire protocol says never to do that…

For high-speed highway driving, you want a RIB tread pattern, not a block tread pattern…

I looked on line for Continental DTS tires and came up empty. Could they be ExtremeContact DWS tires? If so, they appear to be more asymmetric than directional. And they have a “DWS” molded into the second rib from the outboard shoulder. They indicate tread depth. When the S wears away, the tire is not good for snow any more, but OK for Wet and Dry pavement. When the W wears away, they are only good for Dry pavement. Could that be what you feel? Anyway, unless the tires have trouble holding the road, I’d just keep them. At around $250 each, that’s a lot of money to replace them.

The tire wear being described is heel and toe wear. It is caused when a tread elemnt enters the footprint the leading edge is bent away from the footprint and the leading edge gets rounded.

As that same tread element exits the footprint, it holds on until the friction isn’t enough to hold it in contact with the road surface, so it slides out from under the footprint - creating an extra bit of wear.

Tires that are driven tend to get this more than tires that are freerolling.

A certain amount of heel and toe wear is normal, but excessive toe will aggravate the situation resulting in more rapid wear. So don’t be alarmed if you can find it, just be aware that the toe alignment could make the tire more prone to this.

I called it sawtooth, but heal and toe is probably the more common term. It is not cupping or scalloping. Cupping or scalloping is where one block in worn down more than the blocks before and after it. A pattern will appear where these excessively worn blocks repeat at an even intervals around the tire. That is often caused by worn shocks or struts bat can also be caused by an alignment issue.

As for heal and toe wear, or sawtooth, if it is occurring circumferentially, it is not likely due to toe alignment. If it is occurring laterally, then do get the alignment checked.