DansE5004

Left front tire is wearing on the inside tread only. Did have an issue with this tire only losing air so I chesk psi often. No other tires have a wear issue . Tire shops say I do NOT need tires ( imagine that) but did notice the wear pattern on one tire. No issues in steering wheel. Do notice a "hum" like snow tires when breaking or slowing at 20mph. Otherwise...everything seems good. Any suggestions? ( Other than let my mechanic look....which I will do).

otto6457

Most likely cause is excessive toe-out. Excessive negative camber can also cause this but it's much less likely.

Get an alignment from a quality shop that uses a toe presser bar as a standard procedure. Most independent shops do not use a presser bar claiming that their "computer alignment system" doesn't require it. That statement alone establishes that they have limited knowledge of Mercedes or even BMW alignment procedures.

DansE5004

Thanks. I am taking it to my MB independent specialist on Thursday.

vettdvr

For edge wear on only one tire the camber would be off. Inside wear too much Pos Camber, outside too much Neg camber. If it isn't camber then the belt could be off center in the tire. You didn't say what brand of tire.

DansE5004

It is an original Contitouringcontact. Serial number indicates a 2006 production. I really want to change these out but not before we determine if there is an issue. Hoping this is not a major issue so I can spend the dollars on new Michelins.

otto6457

Actually, this is incorrect.

You can get inside wear on only one tire if toe-in is out of spec. A combination of rear toe-in being out of spec along with front toe being out of spec will cause only the inside edge of one front tire to wear. It does this because the rear alignment is causing the vehicle to track towards one direction while the front alignment is trying to make it track in a different direction. One tire on the front is getting a larger percentage of wear as it fights with the rear alignment. Also, if you often drive on highly crowned roads one tire will see more wear if the toe is out of spec due to the uneven tracking of the vehicle. There are also other combinations of alignment angles where incorrect toe-in will cause wear on only one front tire

Also, you have your positive and negative camber wear backwards.

Positive camber is the top of the tires leaned outwards and negative camber is the top of the tires leaned inwards. Too much positive camber causes wear on the outside of the tires. Too much negative camber causes too much wear on the inside of the tires. Your car will pull towards positive camber due to your tire forming a cone towards the outside of the wheel. It's just like laying a cone on it's side and rolling it. It will roll around the point of the cone just as your car will try and rotate around the cone formed by the tire being tipped out at it's top.

Here is a diagram that demonstrates my point.



Cars pull away from negative camber towards the more positive camber. Also, cars tend to pull away from positive caster towards negative caster.