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Tire question.

Dolebludger
Sun, 12 Jul 2020 23:28:54 GMT

All, I have a 2017 C 43 AMG 4matic sedan that I have had for a little over 3 years since new. It came with Perelli 225X35X18 run flat tires on the front (larger tires on the rear of the same make and model). It has only about 14,500 miles on the ODO. So while the rear tires are like new, the front tires are worn down to near the wear bars. The wear is totally even, so I assume I do not have an an allignment problem. Now, I hav never liked these tires. They are only H speed rated, yet they ride rougher than a Z rated tire! I am not concerned about the "run flat" issue as I bought a full sized spare tire and wheel, plus jacks and tire tools, early on. The manual that came with these tires said they were only good for 50 miles flat, and then had to be replaced. That cannot always be quickly done where I live. So I don't want to buy new OEM tires for the front, but don't want the new front tires to throw the 4matic or handling out of balance. Basically, I would w ant the new front tires to be of a higher speed rating, and be non-run flat -- with the idea that the rear tires will eventually be replaced with the same. Any ideas or recommendations?

Alex
Sat, 25 Jul 2020 02:37:11 GMT

Was hoping that someone with experience in a similar year and model car would have replied but since he hasn't, here are my thoughts: I agree with you that replacing the run-flats is sensible, fronts first then the rears when they wear out. It isn't likely that having regular tires in the front and run-flats in the rear for a while is going to bother the 4-matic system during normal use, unless you plan to track the car or do gymkhanas around pylons. As to the speed rating, that this too is moot in normal use. So the thing to do is get an easily available pair of Michelin H-rated tires to fit your 18" front rims. Then do the same for the rear when the time comes. Tire Rack might be able to offer more specific recommendations. An important detail is to have the work done in a place that has the ability to balance the wheels really well, eliminating all trace of vibration at 60 mph. These days this seems to have become an art as well as a science.

Dolebludger
Thu, 06 Aug 2020 17:53:29 GMT

Alex, Thanks. However since I posted this my fronts were looking so shabby that I went ahead and replaced them with the original tires. Just like the originals except they have V speed rating for aome reason. From past exerience, I knew what tires that evenly wear out prematurely is likely caused by too much toe in or toe out, so I got an allignment at a local shop that is very familiar with Mercedes. As I suspected, I had too much toe in. And no, I don't track the car!

Alex
Thu, 06 Aug 2020 20:34:25 GMT

Any idea why both wheels had too much toe in? Could they have been improperly aligned the previous time? If it was a pothole it would have only affected one side.

Dolebludger
Thu, 06 Aug 2020 23:42:07 GMT

Alex, I don’t know. The car was over 3 years old, with only 14K on the odo. No real potholes here, but curbs here were designed for Model Ts. So there has been some contact there. I have no proof that it came from the factory with too much toe in. But it developed it at sometime. ‘Also, I am not convinced thar front alignment is right now. When I drive down a straight roadway with Steering assist on, the steering wheel looks like it is pulling the car back to the left. I shall discuss that with personnel at my usual shop in the near future.

Alex
Fri, 07 Aug 2020 13:42:53 GMT

New cars are never out of alignment or out of balance. They always come perfect in that regard because car factories do so many of the same model that they learn to do it right. It might be is that contrary to the current mechanic’s report, the wheels did not have toe-in and he misaligned them now, creating the pull to the left. Which means that the rapid tire wear you reported was normal for those Pirelli tires on this car. It’s easy to mis-set coordinates on wheel-alignment instruments. A moment’s inattention will do it. And that’s assuming that the numbers displayed in the computer’s data readout for that model are correctly listed by the subscribed data service. Too bad your M-B dealer is so far away because they do alignments pretty good. Let’s see what kind of wear you will get on the new V-rated Pirellis once the correct alignment is achieved. Please report back on your progress. We all have these kinds of problems and can use all the help we can get.

190Efan
Fri, 07 Aug 2020 18:10:36 GMT

While new cars do come from the factory with the correct alignment, they can easily be knocked out of alignment once out on the road by any number of means including, hitting a large object in the road, hitting a curb or large pothole, etc. Determining the alignment issue would also depend on where the tires are worn. Improper tire inflation can also contribute to poor tire wear as well as an alignment issue. Getting only 14,500 miles out of a set of tires does warrant further investigation as that's an unusually low amount of miles for a set of tires.

Dolebludger
Mon, 17 Aug 2020 22:18:00 GMT

Thanks guys, for your comments. I took the car back to the shop that did the alignment. I waited a little while to figure out if the car was pulling to the right, or just alignment off a bit on the steering wheel. It was the latter. Corrections made and all is well on the steering. So I’ll have to wait and see if the front tires last longer than the originals. Even if they don’t, the rear tires (fine now) will probably need changing also. Then, good bye Perelli run flats!