My friend worked as an alignment at a mercedes car service center company. and he noticed that there was a very significant effect of wear on the inside after he had done the alignment. there are 2 models that happen to be E class and S class. only a few happen. And he asked for my help. I think I need your more expert opinion on this
Then he did something wrong.
he made all of them according to fixed specifications and advanced machineries.machine from german.bess barth.
but other cars have no problem. Only certain models
That happen at new car.2018 cars.first time alignment.he adjust a little .then that happen.
First, the camber on many European models is pretty high. My experience says that anything over a degree results in uneven tire wear.
Second, toe is a multiplier. The toe has to right on in order to minimize the effect camber has on tire wear.
Third, once uneven wear starts, it gradually accelerates. Even if you get the alignment back into spec, it will continue to grow.
So perhaps these models have high caster - which adds camber on turning - which, in turn, would made the situation worse. And then there is Ackermann ( various spellings!) - aka toe in change when turning. That could be different, too.
The outer edge looks almost as worn as the inner edge.
That tire could have spent some time under inflated.
I was thinking that as well. I suspect under-inflation too. And alignment won’t help with that.
Also, OP never told us how it was determined that this wear happened after the alignment. Unless he got brand new tires after the alignment, any alignment-caused wear is far more likely to have happened before the alignment. But then after you get it done you’re motivated to look at the tires and that’s when you see the problem that you just didn’t notice before.
That type of wear is from sharp, full-lock turns. Those who spend their time circling parking lots will scuff the inner edge to the steel belts while another person with the same car, same tire, same alignment can experience even wear.
Vehicles with sport type steering and suspension systems have an Ackerman angle that performs best at driving speeds but poor for parking lots.
I have replaced many tires that were scuffed down to the belts.
One major consideration is whether the Mercedes has the 4Matic all wheel drive or just a rear drive. The specks should be different, especially if the 4Matic is biased to the front wheels.
The wear pattern shown could be due to excessive camber, caster or toe out compounded by low tire pressure.
And why did he do that ? Should he not be talking to his supervisor who can contact Mercedes directly for the real answer .
Camber wear won’t appear on just a 1/2" wide spot on the edge of the tire. Uneven camber wear will be shown as a different tread depth of about 1/32" from inside to outside in the tread groves.
It seems to me that it’s not unusual to see a caster spec of 8 degrees or more on Mercedes.
Tq all for you opinion