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Today I purchased (4) new tire’s on my 2012 GL350 after discovering premature inside tread wear. I had 20,000 miles on the tires but the steel belt was showing through the inside tread. The installer said the rear camber was causing the inside tread wear and adjusted the camber as much as he could. I was advised the camber couldn’t be adjusted to the point where the tires would run true with the road.
Any ideas on this and how to correct the rear camber issues.
Please post your VIN so alignment specs can be identified. Rear camber spec is in the neighborhood of -1 degree.
The vehicle should not have to be aligned to the maximum limit of adjustment, something else is wrong. Are the wheels bent? Are the wheels balanced? What is your driving style?
2012 GL350 Vin# 4JGBF2FEXCA785756. Wheels are not bent and all (4) wheels were electronically balanced today. It’s my wife’s car and she drives sensibly. Tire printout 11/05/19
I have not seen a Print-Out like that from the MB dealer alignment machine(s) - so your "alignment" was from a non-MB shop ?
I have seen plenty of well intentioned shops get MB alignments dead wrong - was it a indie that installed and "aligned" your tires 20K/miles ago too ?
On a GL350 - with the "correct" tires and proper inflation - with factory alignment - you should get close to 30K on a tire set - tires aren't made today like they used to be..
Too much rear camber in my opinion, but likely within MB spec. MB specs too much rear camber in my opinion. It increase grip on the rear axle, to create more understeer, to avoid lawsuits. But the extra camber eats tires.
I purchased my tires from Big O Tires and the previous alignment never addressed the rear camber.
What would you consider correct PSI on the front and rear tires keeping in mind my issue with inside tread wear. On my previous set of tires I kept the PSI at 34 front 36 rear.
Last edited by KYBRIGGS82; 11-06-2019 at 12:31 PM.
With air suspension, rear camber should be between -1 deg and -2 deg.
Total toe spec is 33' or 0.55 deg, so technically you have too much total toe.
It doesn't surprise me that excessive inside wear is relatively common to see on this site. M-B specs too much rear camber, too much toe, and too little tire pressure. All of this adds up to lots of grip on the rear axle, but poor tire wear.
I would tell the dealer to align the vehicle to the minimum amounts of camber and toe in the spec range, and air up to 45 psi all around.
As an example, the GLE W166 rear axle spec is -1 deg camber and 0.33 total toe. Alignment spec difference between the GL and GLE is related to 7" longer GL wheelbase, but the tire only knows what angle it is relative to the road, its pressure and the load it carries. When the tire is anything but parallel to the direction of travel (zero toe) and vertical with respect to the road (zero camber), and ignoring for a moment braking, cornering and accelerating, tire wear occurs. The GL is one of the longest wheelbase Mercedes passenger vehicles, hence the relatively extreme alignment settings compared with shorter wheelbase GLE and E-Class alignment settings.
So tire wear is an output, with the goal of avoiding oversteer as the input.
Chassis.. Thank you again for your valuable information. Should I have the dealer adjust the rear toe to .55 from its current setting of .58? Are the current camber settings correct? I will adjust all four tires to 45 PSI.
Thanks
Rear camber is within M-B spec. It would be better if both left and right were the same, and as close to -1 degree as possible.
Total toe should be less than 0.55 deg, I would tell them to bring it into spec.
Bear in mind I run tire pressure higher than M-B spec, and I do so at my own risk, as you would also be doing if you did likewise. I seek longer tire life when inflating to 45 psi.
Chassis
Thanks.. Okay I have an appointment for tomorrow to do the alignment at Big O Tires where I purchased my tires. Big O Tires did the alignment last Tuesday and I will have them set all four tires to the correct toe and camber settings to MB specs. (See image above for current settings)
What is the ideal left rear toe and right rear toe? What should the total toe number be within? In regards to the camber, what is the ideal camber for the rear left and rear right tire? Is the current front left and right camber settings correct? Is the current front left and right toe settings correct?
is thrust angle within MB specs?
Last edited by KYBRIGGS82; 11-07-2019 at 12:22 AM.
The shop should have access to the MB specs if they know what they are doing.
Left and right values should be the same, ideally. This applies to all specs: caster, camber and toe.
My opinion is that all values should be at the minimum of the manufacturer’s spec range. This is because the greater deviation from 0 degrees in all directions results in more tire wear.
Alignment is a trade off of multiple vehicle performance attributes, with safety and stability first priority, then handling and comfort. Tire wear performance on a high priced luxury vehicle usually falls last in line when solving these multiple equations.
Mercedes specs
Front camber: 0 deg to -1 deg
Front caster: no spec
Front total toe: 0.1 deg to 0.38 deg
Rear camber: -1.6 deg to -2.5 deg
Rear total toe: 0.45 deg to 0.55 deg
From your alignment shop's data sheet: (they should know this without you telling them)
Front total toe = in spec
Front camber = not in spec
Rear total toe = not in spec
Rear camber = in spec
Thank again Chassis!
i returned my GL350 to the tire shop and had them complete a realignment to the specs you provided. Hopefully, my new Continental Tire CrossContact LX25 tires will last more than 25,000 miles.
Chassis...
I owe you a great amount of gratitude for your mechanical knowledge and expertise!
Thank you again my friend! My vehicle drives true on the road, the tires are quieter and the ride is awesome.
Now onto the front brakes after being told my front pads are at 10%. If I have more questions I will hit you up!
Best thing I did was have the alignment shop not do at MB specs. Instead, I had them adjust so the tires would go down the road without all the camber so the tires wear evenly. So far with around 30k miles, the tires still look amazing and I don't notice any difference in handling..
Best thing I did was have the alignment shop not do at MB specs. Instead, I had them adjust so the tires would go down the road without all the camber so the tires wear evenly. So far with around 30k miles, the tires still look amazing and I don't notice any difference in handling..
Do point out only adjustment on front of a W164, W166 is "Toe" directional adjustment!!
There is not even offset cam bolts available to allow any Camber change whatsoever.
While excess Toe adjustment will decrease edge wear it dramatically increases overall wear rate.
We saw the need therefore to re-instate from the early 90's full precise front Camber and Caster adjustment.
Two kits manufactured:
#504016-3J $380
This kit simply replaces the upper wishbone inner mounts providing once again precise Camber and Caster (up to 1.5 degrees Positive or Negative).
Includes bush extraction tool, so arms (or front wheels) do not need to be removed to install.
#503816 M $595
This kit replaces the 4 lower arm bushings providing also precise Camber and Caster same time resolving issue with the inner bushings which are prone to premature failure and OEM are expensive to replace. (up to 2 degrees Positive or Negative adjustment).
Also includes bush extraction tool, so arms do not need removal.
For the rear there is Camber (and Toe) adjustment. KMAC rear kit #504026 K $480 doubles the existing adjustment range.
Front was not the issue for the extreme wear and the changes made a real difference in tire wear. I can buy a few sets of tires for what you want for your kits. Doesn't make sense to purchase.
The shop I went to had a kit for the rear. Got me as close as I could go to straight. Seems to be working great. They are the only certified shop in town for MB alignments and my dealership even sends cars to them.
The shop I went to had a kit for the rear. Got me as close as I could go to straight. Seems to be working great. They are the only certified shop in town for MB alignments and my dealership even sends cars to them.
So you installed a camber kit for the rear. What was it and how much did it cost?
11-05-2019, 07:00 PM
