4matic tire wear tolerances
MBWorld Fanatic!
Joined: Sep 2013
Posts: 2,349
Likes: 696
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
I think we might be running this issue into the ground. Over the 187,000 miles I owned it I ran 275-55R17 tires of all wear states on my ML350. The front tires wore so fast that if they weren’t rotated to the back every 3000-5000 miles, they would be down to the steel belts in 12,000 miles. There was never a problem with the transfer case or the differentials. It was still in marketable condition when I traded it in.
IMHO Mercedes 4Matic can well withstand the very minor size difference experienced with tires of different wear states. That is NOT the case on vehicles with 4WD and locking differentials or hubs. We have 4WD trucks for off road use. When the drive train is in locked 4WD configuration, tire diameters of ¼ inch or more on hard surfaces will put extreme stresses on all of the drive train components. Before these trucks get back on the road, the differentials/hubs need to be unlocked and the drive train put back into 2WD.
IMHO Mercedes 4Matic can well withstand the very minor size difference experienced with tires of different wear states. That is NOT the case on vehicles with 4WD and locking differentials or hubs. We have 4WD trucks for off road use. When the drive train is in locked 4WD configuration, tire diameters of ¼ inch or more on hard surfaces will put extreme stresses on all of the drive train components. Before these trucks get back on the road, the differentials/hubs need to be unlocked and the drive train put back into 2WD.
MBWorld Fanatic!
Joined: Sep 2013
Posts: 2,349
Likes: 696
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
That 0.81 inch diameter difference is greater than any wear on a road tire for a GLK could ever be. ¼ inch (8/32 inch) of wear (1/2 inch diameter) takes a tire with 10/32 new tread depth from new to completely worn out.
And the tire with ¼ inch wear can’t be run on the same axle opposite a new tire very long because it is worn out, will not pass safety inspection, and needs replacement.
MBWorld Fanatic!
Joined: Jun 2021
Posts: 1,928
Likes: 524
From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
I think they are using the word "size" to mean the same thing as you would if you said "what size shoe do you wear" or, "what size tire do you have on that axle."
We covered that back in post #3. The difference between a new tire and a worn tire is going to be somewhere between one and two revolutions out of 100. If your differentials can't handle that you'd be restricted to driving in a straight line all the time.
Agreed!
Agreed!
Last edited by John CC; Aug 25, 2022 at 09:40 AM.
Super Member
Joined: Mar 2013
Posts: 915
Likes: 185
Yikes:
It seems there are five generations of Mercedes 4MATIC and three CURRENT versions. A lot of variation possible although the GLKs all had the same, just a change in automatic transmission when the updated GLK came out.
Super Member
Joined: Mar 2013
Posts: 915
Likes: 185
Yikes:
I think we might be running this issue into the ground. Over the 187,000 miles I owned it I ran 275-55R17 tires of all wear states on my ML350. The front tires wore so fast that if they weren’t rotated to the back every 3000-5000 miles, they would be down to the steel belts in 12,000 miles. There was never a problem with the transfer case or the differentials. It was still in marketable condition when I traded it in.
IMHO Mercedes 4Matic can well withstand the very minor size difference experienced with tires of different wear states. That is NOT the case on vehicles with 4WD and locking differentials or hubs. We have 4WD trucks for off road use. When the drive train is in locked 4WD configuration, tire diameters of ¼ inch or more on hard surfaces will put extreme stresses on all of the drive train components. Before these trucks get back on the road, the differentials/hubs need to be unlocked and the drive train put back into 2WD.
IMHO Mercedes 4Matic can well withstand the very minor size difference experienced with tires of different wear states. That is NOT the case on vehicles with 4WD and locking differentials or hubs. We have 4WD trucks for off road use. When the drive train is in locked 4WD configuration, tire diameters of ¼ inch or more on hard surfaces will put extreme stresses on all of the drive train components. Before these trucks get back on the road, the differentials/hubs need to be unlocked and the drive train put back into 2WD.
I think it's very possible your ML may have had a more robust, heavier duty 4MATIC system than the "less premium" GLK/C-Class models. So not so sure how valid a comparison this would be for these purposes.
MBWorld Fanatic!
Joined: Sep 2013
Posts: 2,349
Likes: 696
2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
Good point. The W163 was a design from the 90s. I assumed that the GLK being much more modern would be more capable. But maybe not. The first gen MLs were truly off road capable and had selectable low range like the G-wagons. The GLKs had more limited abilities, maybe a simpler system. But I still think that if it can’t handle 1/4 inch wear difference, that’s a defect on a passenger vehicle.
Junior Member
Joined: Jul 2015
Posts: 41
Likes: 15
From: Las Vegas
2014 and 2015 GLK250
I can't find the reference now but I recall a 4/32 tolerance. In support of this I reviewed the CPO paperwork on my wife's 2014 GLK. The measured tire tread depths when I bought the car were LF 5/32, RF 9/32, RR 7/32, and LR 7/32. So a Mercedes technician and his service manager signed off on this difference. Strangely, after the 250 mile drive home I measured the tires myself and found the LF to be a 4/32. So, I went to Discount Tire and had them replace three of the tires. And no, it wasn't worth the hassle to argue with the dealer because of the distance.
Regarding repairs, I go with the tire manufacturer's recommendations. Tire Rack is always a good source (see attachment).
Tire Rack tech advice
Regarding repairs, I go with the tire manufacturer's recommendations. Tire Rack is always a good source (see attachment).
Tire Rack tech advice
MB World Stories
The Best of Mercedes & AMG
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
Newbie
Joined: Jul 2023
Posts: 3
Likes: 0
2017 Mercedes S-Class
Unlike some dealerships, I've never heard of or experienced Costco trying to scam anyone and it sounds as if they were covering themselves and being over-cautious. It's fairly well accepted that mounting a different diameter tire on an AWD vehicle can result in long-term damage to the differential and couplings by overheating them. After 20K mi there's probably enough wear on your tires to appreciably change their diameter compared to a new one.
To quote Cars.com (definitely not scam artists) "Some manufacturers of all-wheel-drive vehicles recommend that all four tires be replaced, not just one or two, because a new tire will have a larger overall diameter than the other tires. The ones that have lost just a few 32nds of tread depth will spin faster than the new one, and the difference could cause an AWD system to engage on dry pavement and possibly damage the system."
As for refusing to repair your tire, that's a bit more subjective. The leak is at a previous repair which means that the original repair was done badly and possibly caused more damage to the tire. I don't think that many responsible/reputable repair shops would be willing to attempt another fix and risk a high-speed blowout.
If you can find a shop willing to "repair" your tire, good for you. Drive safely.
To quote Cars.com (definitely not scam artists) "Some manufacturers of all-wheel-drive vehicles recommend that all four tires be replaced, not just one or two, because a new tire will have a larger overall diameter than the other tires. The ones that have lost just a few 32nds of tread depth will spin faster than the new one, and the difference could cause an AWD system to engage on dry pavement and possibly damage the system."
As for refusing to repair your tire, that's a bit more subjective. The leak is at a previous repair which means that the original repair was done badly and possibly caused more damage to the tire. I don't think that many responsible/reputable repair shops would be willing to attempt another fix and risk a high-speed blowout.
If you can find a shop willing to "repair" your tire, good for you. Drive safely.
A staggered Mercedes 4-matic set-up from the factory is out more than 3/32"
3/32" = 0.094" out
One example of many 2016 S-class front 245/40r20 rear 275/35r20 = diameter front 27.72- diameter rear 27.58 = 0.14 of a inch out
Last edited by Megalomaniac1; Jul 23, 2023 at 09:06 AM. Reason: spelling
