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Like most on here, even with regular tire rotation I would lose valuable rubber to shoulder wear. I concluded this was because the rear suspension is set at negative camber. I recall in one alignment the rear camber was about -2 degrees. That might be useful in a track car, but for a truck that is running on the highway, and especially with lower profile tires, it will result in inside shoulder wear.
I found out the rear camber is adjustable, just not by very much. I posted a thread on doing the adjustment; I don't have a camber jig, so I just cranked it all the way to the most positive setting.
I put a set of winter tires on last November, and ran the truck about 7k miles. About half that was highway, on a road trip. This is important because the camber will go more negative when the suspension lowers at highway speeds. Since some of the road trip went to warmer areas, the wear was probably excessive for the miles. I recently took off the snow tires, and just now went to the storage locker to measure the tread depth. What I found was interesting enough I thought it was worth a new thread.
Here are the measurements. I unfortunately did not keep a record of which tires were front and which rear, but the ones that wore more were almost certainly the ones on the rear. Since the tires are unidirectional, I know which ones were passenger side and which driver. There are three measurements, outside, center, inside.
O / C / I
D 0.330 0.373 0.342
D 0.315 0.340 0.324
P 0.316 0.356 0.347
P 0.318 0.318 0.328
Observations:
1) Across the board the tires are underinflated. I recall setting them at 35 front 40 rear, but it may have been colder later.
2) I might have messed up the driver / passenger distinction; it doesn't make sense that the passenger side wore less than the driver.- although that could be due to alignment side to side. Hey, it was getting dark in the storage locker.
3) The front wheels (rows 1 and 3) clearly have a bias to wearing the outside more than the inside.
4) The rear wheels (2 and 4) now also have a bias to wearing the outside! This means that the rear camber adjustment range is sufficient to eliminate inside shoulder wear - and with the right adjustment, you should be able to get slight rear wear that offsets the front tires' tendency to wear the outside shoulder. This is great news and only calls for you to either get the tools to adjust it yourself, or to find an alignment shop that is willing to work with you and not just shrug and say it's in spec. If you have a flat concrete floor (doesn't need to be level, just flat) you can probably do a passable job adjusting the camber. Or just do it by trial and error; go to the maximum camber setting and back it off to get slight inside shoulder wear bias.
The bottom line is worth repeating: The rear camber is adjustable, and it is adjustable to within the range you could probably get about perfectly even tire wear.
It is a puzzle but it is unmistakeable. The passenger side tires wear faster than the driver side. I can't think of any weight distribution reason that would cause this. The battery is on the passenger side but otherwise it seems pretty even. Possibly because the roads are typically crowned to drain to the right, so the vehicle is normally leaning slightly to that side?
Do you have camber and toe measurements from an alignment machine?
Traffic generally flows with more right turns these days. Could be one reason for passenger side wear in LHD market. Right turn = smaller turn radius from the point of view of the passenger tire.
Do you have active lane keeping assist? Do you have Distronic?
I don't know how to relate where my alignment is set up at, but I get nice and even tire wear, coming up on 40K miles with maybe 5K to 10K left on them. If there's a way to relay where mine are set at, I'd be glad to provide that info.
For the W164X (and every model Mercedes Benz 1968 to 2021) we manufacture both Front and Rear kits allowing to adjust “tire contact angles” - spread load more evenly !
This need was brought about to cater for other then showroom height conditions - high cambered roads, altered height through load carrying or lowering, fitting wide profile tires (or curb knock damage).
Front KMAC kit provides both “Camber and Caster” adjustment for the 1st. time and also replaces the 4 front highest wearing suspension bushes at the same time which are subject to premature failure and OEM are very expensive to replace.
While the KMAC rear (Camber and Toe) “doubles the existing adjustment range”. Like front are also precise single wrench adjustable. Bush extraction tool is included allowing to be fitted without need for arm removal.
W164/X Front kit CAMBER & CASTER #503716 P $695
Also alternative “upper wishbone inner bush adjuster, also CAMBER & CASTER #504016-2K $480
It is a puzzle but it is unmistakeable. The passenger side tires wear faster than the driver side. I can't think of any weight distribution reason that would cause this. The battery is on the passenger side but otherwise it seems pretty even. Possibly because the roads are typically crowned to drain to the right, so the vehicle is normally leaning slightly to that side?
Originally Posted by chassis
Do you have camber and toe measurements from an alignment machine?
Traffic generally flows with more right turns these days. Could be one reason for passenger side wear in LHD market. Right turn = smaller turn radius from the point of view of the passenger tire.
Do you have active lane keeping assist? Do you have Distronic?
Only the MB does this, I have 5 cars, they all ride in the same roads. I don’t buy your theory.
Do you have camber and toe measurements from an alignment machine?
Traffic generally flows with more right turns these days. Could be one reason for passenger side wear in LHD market. Right turn = smaller turn radius from the point of view of the passenger tire.
Do you have active lane keeping assist? Do you have Distronic?
No on the active assist, no on the Distronic.
I did have a shop check the alignment. Front camber is -1 both sides, toe is 0.07 (positive is toe-in?), both sides. Rear toe 0.14, both sides. Rear camber was -2.1. No idea what it is now. Might take it to a shop, dunno.
I should probably re-check the tread depth measurements. The tires are just stacked in my storage unit. It can be hard to get accurate measurements. It seems like a clear pattern, though.
I don't know how to relate where my alignment is set up at, but I get nice and even tire wear, coming up on 40K miles with maybe 5K to 10K left on them. If there's a way to relay where mine are set at, I'd be glad to provide that info.
I'm assuming you find more tire wear on the rear than the front; do you rotate side to side also?
I'm assuming you find more tire wear on the rear than the front; do you rotate side to side also?
Honestly, not sure. I do most of my own maintenance and repairs, but I got free rotations with the purchase of the tires so I let the shop do it and the only thing I double check is the stud torque. I have it done every 5K miles.
I rechecked the measurements. It's difficult to get consistent results with the gauge, but the pattern matches what I measured previously.
Two things are unmistakeable:
1) If you push the rear camber to the most positive / least negative you can get pretty near even wear across the tire.
1a) Note that you would not see the shoulder wear with regular tire rotation, as the unevenly worn tire will not sit flat when moved to an evenly-wearing location (e.g. the front). Handling is worsened by tires not sitting flat, though.
2) The passenger side wears faster than the driver side
2a) At least in Boise in the winter, on snow tires
Last edited by eric_in_sd; Apr 3, 2021 at 06:48 PM.
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