Very bad inner tyre wear

[Dieselman]

Is this a recognised effect? I have very similar issues as the OP.

When did you last fit new springs and dampers, springs in particular?

 

[AANDYY]

I Haven't. On the rear, new on the front about 3 years ago.

 

[Dieselman]

Which are wearing and have you had the camber set on the front?

 

[AANDYY]

Mine are wearing on the rear like the OP's.
Fronts wear a little on the inside edges but the tyres have been on longer (35000 miles-ish).
I can only assume the camber was set on the front when the 4 wheel geometry was done about 2 years ago.

 

[Dieselman]

Mine are wearing on the rear like the OP's.
Fronts wear a little on the inside edges but the tyres have been on longer (25000 miles-ish).
I can only assume the camber was set on the front when the 4 wheel geometry was done about 2 years ago.

I wouldn't automatically assume that, to set the camber it needs offset bolts, which most centres won't fit.

I suspect your ride height may be getting a bit low at the rear, but it's worth checking the toe setting as well.

 

[prprandall51]

Is this a recognised effect? I have very similar issues as the OP.
I had the 4 wheel geometry done about 2 years ago, I straddle the speed cushions (ironic name!) nearly every day one especially is bad, I have to slow to about 5-10 mph (council not interested in my complaint to them).

Yes, it is a known issue. You can read about it extensively at Honest John on the Telegraph website. It is also exactly what happened to my BMW because I used to straddle them.

The sloping sides of the cushions grind away the inner edges of the tyres (basically, the whole weight of the car is supported by the sidewalls) and, if you travel over the cushions fast enough then their shape effectively acts as a wedge driving the wheel alignment out creating excessive positive camber.

 

[John]

Mine did need one bolt to bring it into line (suspected it might need 3 at the start - so glad it only did need one).

 

[wheels-inmotion]

I'm not so sure speed bumps or cushions are the criminal.

Speed bumps are designed so you traverse over them with the wheels dead ahead, the suspension is more than able to absorb this providing it's done at reasonable speed.

Cushions are debatable, personally i feel the tyre will deflect without transmitting energy at a sufficient level to influence the wheel/ chassis. I'm not so confident if run-flat tyres are fitted though.

If the rear cambers are symmetrically incorrect and the car has some mileage then one could assume the coils have sagged and migrated the camber. The reason the rear camber is not adjustable is because it's not expected to go wrong naturally.

Conformation the coils have sagged would come from measuring the trim height. This is the distance between the sprung/ unsprung chassis but unfortunately MB has not released this information.

 

[BlackC55]

It's not just the equipment it's the operator too.

 

[Dieselman]

It's not just the equipment it's the operator too.

That's exactly what I said to Mrs Dm.

 

[wheels-inmotion]

Absolutely agree.... I train the trainers in the "fast-fit" arena and it's scary how basic their knowledge is, anything away from basic problems falls totally out of sight. In fact i had the largest FF in my national network of calibration centers and i've dropped them all from my list.

 

[BlackC55]

Absolutely agree.... I train the trainers in the "fast-fit" arena and it's scary how basic their knowledge is, anything away from basic problems falls totally out of sight. In fact i had the largest FF in my national network of calibration centers and i've dropped them all from my list.

Some of these wheel alignment places can't differentiate between castor, camber and toe. Read a book ffs.

 

[wheels-inmotion]

Totally agree....

I have argued with the machine manufacturers not to allow a short cut in information gathering? At the moment the machine will allow primary measurements and/ or secondary measurements. The secondary measurements holds the most information, so vital in my opinion.

Thanks to the Internet most owners now know wheel alignment is a total wast of time and a con, it's line of sight is linear, so 1D in a 3D world.

Secondary measurements involve angle like.....

1: Castor: Duties include directional stability/ returnability/ camber migration on lock and other communications toward the sprung chassis.

2: SAI aka KPI: Steering Axis Inclination/ King Pin Inclination: Is totally avoided due to it measured complexity?

SAI/KPI is the perpendicular position of the unsprung pivotal point, or in other words the perpendicular angle of the lower ball joints pick up point.

SAI/KPI is one of the most important angles within the realm of geometry but rarely measured threw ignorance.

And then we have the Ackermann angle, toe-out-on-turns, lock angle, roll force lever, set-back, symmetry and so on........

Most of the secondary angles are not adjustable but if measured opens a catalogue of information: Example> Within the information an angle called TOOT/ Toe-Out-On-Turns will tell me the car has a bent steering arm without me even looking at the arm.

We/ You entrust operators out there to drive these fantastic machines because "you" are not in the position to understand datum gathered and why should you be or need to?. The sad fact is most times the datum is incomplete or miss-read leaving you on a quest seeking solution.

I train the staff/ instructors in the biggest fast-fit company in the EU and i currently have around 40 of their centres in my national network but due to constant violation of my protocol i'm removing them from my list.... all 40.

Have i failed?.... I think yes. Could i have done better in my training? No because i couldn't police the operation.

 

[vass234]

Just had a blowout of the rear tyre of my W208 CLK 230 cabriolet with 255/35 x 18 tyres. The inner part of the tyre was down to the wire and beyond. The other tyre was the same. Both had done only 6500 miles from new. The car seems to sit low at the rear and the camber is noticebaly out, (top of tyre leaning in). I have ordered new springs as the rear camber is not adjustable. I'll let you know how this works out.

 

[RichAJ]

Unless something changed i dont know about between the coupé and the cab the rear camber is very much adjustable.. Merc call it a full 4 wheel alignment but they have the equipment to adjust the rear camber because i had it done when i changed the springs and wheels, it needs doing because it destroys tyres if its not right... i know this from my previous 230 lol.

 

[kth286]

Unless something changed i dont know about between the coupé and the cab the rear camber is very much adjustable.. Merc call it a full 4 wheel alignment but they have the equipment to adjust the rear camber because i had it done when i changed the springs and wheels, it needs doing because it destroys tyres if its not right... i know this from my previous 230 lol.

the Merc multi link rear suspension is same design for all cars since early
80's when it was introduced on 190 model.

There is nil adjustment for rear camber.

There is adjustment for rear toe.

The above poster may find that it is the toe adjustment that has seized
within the bolt/bush assembly, and causing the inner side tyre wear, because of excessive toe in.