Left rear tyre keeps getting quickly worn down excessively on inside edge. Average `lifespan' is around 6,000 miles VS 18,000 for the other 3 tyres.

If it is only wearing on the inside edge your wheel alignment is wrong. The most common cause is the tyre is 'toe out'. The tyre isn't pointing straight ahead like the one on the other side. It is sticking out at the front edge.
Take the car to a good tyre and suspension specialist and get your 'tracking' and 'alignment' checked. They should check your track rod ends and suspension mounts as well.

It should be possible to gain a rough idea of the problem from the tyre wear.

Choppy scalloped type wear suggests defective shocks or excessive wheel imbalance.

Wear of both shoulders or edges of a tyre or the centre of the tread indicates incorrect tyre pressures.

If both tyres are displaying a similar wear pattern on the same inside or outside shoulder indicates incorrect toe setting.

If one tyre has a shoulder that is wearing it indicates an incorrect camber angle.

If both tyres are wearing differently the problem is likely to be a combination.

The rear alignment of some cars is adjustable and slight misalignment can be corrected but often rectification comes down to replacing parts or even using a body jack to move mounting points.

I suggest you book your car in for a 4-wheel alignment check.

I am not an Mercedes expert, but if your rear axle is not solid from one side to the other, you have one of a number of hinged floating rear axles. These may simply require an alignment, just as the front end requires.

With excess wear on the inside track of the tires, the inside of the tire is pitched down lower than the outside edge. Most rear tires are set to run level or slightly pitched to improve handling.

If your rear assembly is not adjustable, the connecting bushings are worn on the linked suspension or the rear axle bearings have excess clearance.

Go somewhere to have a 4 wheel alignment, not to be confused with 4 wheel drive.

Please rate my info.

out side edge wear usually means positive camber, dont know if rear camber is adjustable on your car. alignment specs arnt going to help you unless you have an aligment rack

It sounds like a classic case of tyres being under inflated, check with car manual or tyre supplier for the correct pressure's

Yes there is adjustment. You need to get the alignment checked out. It could be worn bushes and/or damage to the suspension linkages and struts.

Hello there:
The only possibility is that you need a camber adjustment. If that were the case, the tires would be wearing more on the inside edges. If they're not, either ease up on the gas a little bit, or just put $2 a week in a piggy bank for your next set of rear tires, and don't worry about it. the tires that come with this car are made of a relatively soft compound. The softer the rubber, the goo-ier the tires, and the more the car "sticks" to the road. That's one of the reasons you can drive down circular parking garage ramps at 65 mph in this car. The downside of softer tires is that they wear out faster. So it may be a combination of your driving and the type of tires you have.

Brad

1. It's hard to say without looking at the vehicle (and test driving it) but more than likely the front end is badly out of alignment. ( If the car has been in a significant front end accident and badly repaired then this could also be a source of the problem as the alignment may not be capable of being properly set).

2. The first thing to do is take the car to a specialist suspension and steering shop and have the wheel alignment checked and adjusted to factory specs. Normally this is not expensive for a straight forward alignment but price depends on the shop. A good suspension shop will also identify if there are any wear problems with the steering or suspension that need attention

3. Older drivers sometimes frequently hit kerbs when parking their cars. This will throw out the front wheel alignment every time (and damage tyres) so it must always be avoided. Scrubbed.scuffed tyre side walls are an indication of this as well as scratched wheel rim edges.

4. Some drivers never check tyre pressures. Low tyre pressures will cause much greater tyre wear as there is more friction. (It will also make steering heavier, place undue stress on the steering components, cause the car to handle badly and result in much higher fuel consumption).
The lady needs to ensure her car has at least 32 lbs pressure in both front tyres and at least 30lbs in the rear (which carries less weight). The pressures must be set with COLD tyres. Manufacturer optimum spec tyre pressures are usually set for comfort. These can be safely exceeded by a few pounds. It is far safer (and more economical) to run slightly higher pressures than a setting that is too low. (A good tyre will run all day with 38-40 pounds pressure and 36-38 is quite safe).

5. Worn out shock absorbers will also contribute to abnormal tyre wear. 70000 miles of average driving will see out a set of shocks. (Personally I would not leave them that long as the factory shocks are generally of average quality on this type of car)..

That's the best I can do Brad without seeing the car so I hope this helps some. Hopefully a good wheel alignment will fix the problem but make sure the tyre pressures are kept up as well. If the shocks are worn out they will also need to be replaced if the car is to be roadworthy.

Cheers Sean

There should be a sticker on your door, or door post, or glove box, that tells recommended pressures. I'm guessing 30 to 35 psi. When in doubt, I go few psi lower than max. stamped on tire to start, then back it down 2 psi or so at a time until I get the ride, feel & handling that I like, then I watch the tread after a good drive down the highway. Dark on outside edges of tires, lighter in middle,air too low, add 2 psi at a time. Dark in center but lighter on outside edges, too much, remove 2 psi. & retry. Good ride, good handling, tread same all across, bingo, then I note it. Add few more pounds when carrying full load, back off to my notes for normal driving. Ride feels rougher than normal over bumps, lower it 2 psi. etc. etc. etc.

When this happens it means that you have a convergence problem. Go to a tyre fitter, mention the problem, and after fitting the tyre ask to perform a balancing and convergence setup on rear wheels, this should fix the problem.