slavach

So I recently bought a 2013 GLK 350 4matic, although all tires were fairly new, i just noticed rear passenger side was mismatched and had a 55 aspect ratio intead of 50 like the other three. I immediately purchased another similar tire of the proper size but still mismatched. Will this cause damage to the 4matic system or anything else?

MJ50

moved to X204 forum...
you bought new tire and it's still 55 profile and not 50???

Mmr1

They need to be the same diameter or it’s a possibility the 4matic system will see it as slipping and try to constantly adjust. Possibly damaging something

John CC

What is the whole number (e.g. 235/50-19) for each tire? It's the rolling circumference that matters, not the aspect ratio.

Odd Piggy

We can twist ourselves into some tight knots over this issue!
If the tire is the proper size, then the the mis match will be only in brand and/or tread pattern or possible load range. Tread pattern can have some braking and traction impact, but that is likely to be noticeable only in the most extreme conditions.

slavach

No. The new tire is a 50. They are now all 235/50/19. But the new one is not a michelin like the others although it has a similar tread pattern.

John CC

OK, that will probably be fine. If it were my car, I'd probably buy two matching tires and put them on the back. Save the third one in case one of the others needs to be replaced prematurely.

NYCGLK

Every time you turn your wheels are running different speeds/distances. If it was big enough issue your ESP would be freaking out.

John CC

GKL turning radius is 19' and the track is 5' so the inner tire at full lock is turning about 80% speed and distance of the outer one. The difference between a 235/55-19 and a 235/50-19 is about 4%.