Baloo588

I have 17k miles on my Pirelli Scorpion Verde all season tires in size 19 inch on my 2013 Ml350 bluetec. They are smooth and were very quiet when new. However, lately, there is some sound coming somewhere in the car when cruising on smooth tarmacs 35-75 mph and it picks up with increasing speed. It sounds like um-um-um. It doesn't change with lane changing either left or right so I doubt its wheel bearings. I have had that issues before on other cars. This sound does not go away with putting transmission in neutral so its no the engine or transmission. I am wondering if its the tires cupping or feathering? Anyone can chime in and tell me of other possibilities? The tires are well balanced with no vibration. However I have not rotated them yet but they are fairly new with alot of thread left and I did not hear this before about few months ago....I am second guessing these Pirelli tires.

Baloo588

Update:

Dealership confirmed that these Pirellis are cupping a bit in the front causing that rotational noise. Its not a good tire or brand. I have had michelins on my older ML350s and will get them again this fall. No more Pirellis for me. No matter how well you take care of them, they are not good for longevity.

jtorrebl

That has nothing to do with tire brand and much as it has to do with an alignment. And not necessarily the side to side alignment

JRHolt

You stated that you put 17K miles on them without rotating them. That could very well be part of the problem.

Also as jtorrebl mentioned, your alignment may be off. Did the dealership check it?

Another thing to consider is the tire pressure you are running. This can considerably effect tire wear.

Baloo588

Hey guys,

Yes my alignment is perfect. Unusual for this to happen. I check my tire pressure every month. I didnt need to rotate the tires on my older mL350s with the continental and michelins and the car is AWD and all 4 tires wore evenly on the 2006 and 2010 ML350s and I got 35-40k miles out of each set of tires on both of the older MLs with the 19 inch rims and same tire sizes. I do about 25k miles a year and most tires including Michelins and Continentals on my Audi, BMW, and Lexus have not had this cupping. HOWEVER, my 2006 Audi A8L did have Pirelli P6s and EVEN with rotations they caused this noise around halfway through their lifecycle. The alignment was good and I do not hit any curbs or potholes. I balance them every 10k miles. I am very thorough with my cars so its the tires unfortunately. Happens with certain brand or types of tires.

Anyways, I will be getting my long time favorite Michelin Latitude Tour HP in few months and dump these pirellis. I like a smooth and quiet ride and I make sure my tires/wheels are perfectly balanced and I check my alignments within each year.

shortspark

I have been driving cars for 50 years and always rotated my tires every 5,000 miles or so. I decided not to do that any more when I bought the ML350. Unlike FWD cars where the rear wheels basically get pulled along for the ride, our 4matic tires should wear fairly evenly although the front tires will have a bit more wear because they turn. I check them with a tire thread gauge and they in fact are all wearing the same across every area of the tire.

Another reason I am letting them go is that they are in perfect balance and riding very well for what they are (Dunlops). The last reason is that I really want a nice set of my favorite tire (Michelin) and don't care if I replace the Dunlops prematurely. If I get 30,000 miles out of them without rotating I will be happy.

Rotating tires has no effect on alignment or any other mechanical issue. The only reason to rotate tires is to even out wear so your tires last longer but I don't care about that with these Dunlops. Since you say your tires are well balanced, I think your problem is being caused by alignment or something mechanical like joints or bearings, not the tire itself.

Baloo588

Hi,

Thank you for your input. I do agree with the first paragraphs from my experience with the recent generation ML350s and their tire wearing out evenly which is why I never rotated them. The new ML tires are wearing out evenly but the fronts are cupping so I told them to check alignment but I am at 17,000 miles and I don't want to pay money now and just burn through these pirellis in few months (2k miles a month on avg) and get the Michelins and do road force balancing and proper 4WD alignment then.

Baloo588

Well, it was in fact due to bad camber and toe-out of my front wheels. I complained to dealer to do the alignment because of my feathering and that the car was fairly new and less than 8 months old. The alignment had to be out from the factory as I have not used this car anywhere else except on smooth highways between home and work without any potholes or bumps. They replaced a left front caster bolt and did alignment along with rotation of the front wheel/tires to the rear. The noise is there but alot less (70% less) now and I can at leas wear them in properly from this point forward until they are done in approx 10k miles. I know that once tires are cupped they cannot be reversed but can be minimized for the time being. Thank you everyone who commented here.

PS: Pirellis are not that bad but just a bit firm and more noisier than Michelins as they get older.

JRHolt

Thanks for the update