Ryan1

Hey Guys --Does anyone have any experience with oversized aftermarket wheels/tires on the 4Matic set ups? I want to fit my 2014 CLS63-S with HRE's on 255/35/19 (stock size) and 305/30/19 (two sizes wider than stock) on the rear.... Pretty straight forward on the RWD cars, but my dealer just told me this about the 4Matic's...

"... the issue will come up when the vehicle exceeds 60 MPH or more, the traction control light will come on and disable cruise control. The higher rate of speed, the difference in rotation between the front and rear wheels, the vehicle will think that there is some issue to traction and will compensate"

Has anyone had any issues with this on any of the 4Matic's? If this is true, I'd be stuck running stock tire sizes, right?

clkwork

The width doesn't matter, it's the total diameter that changes rotational speed... in this case the new tires are actually smaller (30mm vs 35mm profile). That's not a huge deal but in the long run it can damage the center differential/transfer case.

Ryan1

I understand your point, but the width does actually matter for any given profile (i.e. 30, 35, etc.). If both tires are 30 profile, the width directly impacts the rolling diameter. My stock rear tires are 285/30... that is the profile is 30% of the 285. If I jump to 305, the profile is 30% of the 305, thus increasing the rolling diameter.

Using the calculator on this site it says the stock tires (255/35/19 & 285/30/19) vary in rolling diameter by -1.15%. One would assume this is how the car is calibrated from the factory? If I change the rears to 305/30/19, the variance changes to +0.68%. That's a 1.83% swing overall. Does not sound like much, but what are the factory tolerances for the 4Matic?

otakki

This issue is similar to something I have brought up before. So if you get a non-repairable puncture on just one tire, does that mean you have to replace all 4 tires since the diameter between the new and old tires are different.

clkwork

If you have more than a couple thousand miles on them then yes, they should all be replaced. Also pay close attention to tire pressures for the same reason.

As for the OP, another thing to remember is your warranty... even if it doesn't stress the transfer case all that much just remember that if anything ever happened that's the first thing they would blame.

95viper

1. Click on Pricing and Spec and compare diameters of OEM versus what you are looking to do. http://www.michelinman.com/tire-sele...t/tire-details

2. Contact SirBoostALot. He just jammed 255/35/20's and 315/30/20's on his W219. That is one heck of a difference over OEM. See how he is doing.

hyperion667

this is where you would want the 'experts' to chime in...........