I have a MB E320, 4 matic and am being told that I must purchase 4 new tires or risk damaging the transmission. (the two front tires are still good) Has anyone ever heard of this?
Your car has rear wheel drive. You only need two tires. The admonishment of ruining the transmission applies only to AWD vehicles.
4 Matic = AWD. Yes you need to keep the tires the same or you risk damaging the center diff
Yup…They are correct. A AWD system can be damaged if different size tires are put on.
The OP said it was a 4matic, replace all four tires. You really do not want to pay for a replacement transmission for that car. In the future, consider rotating the tires so they wear evenly.
FoDaddy is correct that your AWD vehicle requires that the tires be very closely matched in circumference in order to avoid damaging the center differential.
You have two options. You could buy 4 new tires, as you were already advised. Or, you could order two of the exact same tires that are mounted on the front wheels, and have them “shaved”. The more sophisticated tire dealers do have the capability to do this, or at least they can have the tires sent out to someone who can shave them so that they are the same circumference as the front tires.
But, why take out word for it? Take out your Owner’s Manual, and thoroughly read the sections regarding changing flat tires, replacing tires, operation of the AWD section, and possibly some other sections in order to find the information relating to this issue. Failure to follow that advice will mean repairs that would be pricey on any AWD vehicle. On a Mercedes those repairs could be in the category of “Second Mortgage” expensive.
Incidentally, if the tires on the front wheels are substantially better than the tires on the rear, this indicates that you have not been rotating them as per the Mercedes maintenance schedule. This means that you need to pay more attention to that maintenance schedule and/or change the facility where the maintenance is done. Your mechanic should be aware of the need for regular tire rotation on an AWD vehicle, and if he is not aware of this…well, it is not a very good sign.
How many miles on your current tires? If there’s less than 10~15k miles on them, I’d look into having 2 new tires(the exact same type the other 2 are) shaved to match the others.
Also, you got a Mercedes, and you want to skimp on tires?!