Currently got the factory staggered setup (225/45/17 front and 245/40/17 rear). When it's time to get new tires, I was thinking of using 255/40/17 on the rear - it is actually a closer match in overall diameter to the front. Anybody running this size? Any issues?

Anyone?

I think your mph goes off the rear...whats your reason for switching?

1. 255/40/17 is closer in overall diameter to 225/45/17
2. The wife keeps curbing the rear wheels, so slightly more rubber might give better protection against curb rash.

I'm confused with what the front diameter has to do with the rear diameter I thought the speedo is measured off the drive wheels. In this case the rear wheels. Your tires will be too small in the back.

If you dont mind the speedo being off a bit, then that works

I'm not worried about the speedo - the difference between 245/40 (OEM) and 255/40 is very small.

The reason I referenced front diameter is that I thought that when it comes to AWD, the wheel diameters (front and back) should be kept identical. Otherwise it puts additional strain on the differential, but I'm not really all that well versed on how modern day 4Matic works in that respect.

Too small? Just the opposite. The factory size is 245/40 and I plan on using 255/40.

sorry I mean big lol. And yeah I've heard that too about AWD something about Traction control not operating correctly... but the i thought your originals were staggered?

won't be any issue but I doubt it will prevent curb issues. They need to be taken up with the operator
Or look for those new types of tires with the rim protector feature.

They are, and I plan to keep it that way. Fronts will remain 225/45, and rears will be 255/40.

Pete. Not an expert but I don't see a problem. Your rears will be 10mm wider and only slightly higher but as somebody else said try to also get tires with rim protectors.