tread depth difference an issue on 4MATIC?
 

2010 E550 4MATIC - Rear tires were making noise. Worn unevenly. Dealership replaced two rear tires - same manufacturer as the front tires, but different model - (both back tires are the same make and model - some confusion on this in the thread) so different tread patterns from the front tires to the back tires - seems as though this was not correct, if anyone can speak to this issue as well as my question(s) below. I asked dealership if all 4 needed replaced at the same time. They said no. Go to private Mercedes mechanic who tells me front tires are 6/32 tread depth, rear tires are 10/32 tread depth and that with the 4MATIC, all four tires need changed at the same time since all-wheel drive on Mercedes is not very forgiving with different tread depths and this stresses the all-wheel drive system and could cause failure to the tune of $6-7K. Any thoughts on this? True, not true? Did the dealership screw up royally by not replacing all 4 tires? Thank you!

Thank you so much. And, I didn't think about tire pressure differences...it all sounded a bit pushy to me. The only ones you can trust are your mbworld.org pals. Rock on!

Thank you for your quick reply and your input! It all sounded a little pushy and a bit dramatic...glad to be able to come to the forum of friends and get the true scoop! Cheers!

Welcome.

Another something to consider is MB's are heavy, tire eating machines.........that look really good while eating tires :)

I really surprised about the 2 different rear tires - doesn't speak too well about the dealer. Regardless if they replaced them under warranty.

No issue if rear axle tires have more or less tread left than front. Bigger issue is what caused the uneven wear. Did you get an alignment done to correct any issues?

I was driving on 2 rear legally bald tires and 2 fronts that had about 25% tread left.I drove like this for an entire winter. 2010 4matic E550. I got new tires last year. Michelin Pilot Sport 3 A/S+

Mercedes Benzs have hundreds if not thousands of sensors. But a tread depth measuring sensor (and associated software) is not one of them.

So, there is no way a 4-matic vehicle can measure differences in performances between axles, or compensate its performance... based on the physical capabilities and limitations of the tires themselves. i.e., traction control sensors work only to maintain traction, regardless of tire specs between axles.

The private mechanic does not know what he is talking about...

Rule of thumb says MB allows for 4% difference between tires rpm before it start dashboard discoteque.
Surprisingly 6 mm thread difference will not come to 4%. Than usually first thing to notice is CC kicking off at speeds above 60 mph.
New tires on front or rear is whole other dispute.
Michelin advise putting new tires on the rear.
In my younger years I was driving in 4-seasons, where tire thread played big role.
So 1 time I put new tires on rear and wear on front.
For next couple of days, driving on slooshy show I could not control my car on turns and each braking was ending with my back sweating.
Next day I put new tires on front and even moving the car from start was a bit harder, the turning and braking was dependable.