[BlueSander]

Hi guys,

I did a quick search but it seems like the information isn't exactly clear.

Could you guys educate me on how the car is programed to deal with the power distribution in a square vs staggered setup? The M550 came with 20" staggered and my winter setup is square 19". The car seems fine but I start to wonder if there could potentially some long term problem this could cause. My friend told me that I should not be doing this especially in the M550.

Also, just recently I have started to feel the speedometer is reading much higher speed on my winter tires. Is there any way we can adjust this so the car knows what to do?

Thanks!

[tjbuggy2b]

It has a ~1% allowance in front/rear diameter difference. I haven't heard of anyone saying anything about power distribution doing any compensation. Based on some seat-of-the-pants dyno-ing when turning to enter traffic, it seems to be at least partially based on how much throttle you give it, as to whether it applies power to the front axle. There is a noticeable additional turn-in that half way through the turn, as I apply additional throttle. It feels like the fronts grabbing more traction and pulling the front end around.

Besides that, I'd wager that the it's monitoring front/rear slippage, which is where the 1% allowance comes into play. Basically, if front/rear rotation is >1%, it applies torque to the front end.

This is all speculation, btw. I'm no engineer.

[BlueSander]

Got you. Thanks. I'm also toying with the idea of sizing up the sidewall on the 20" set to avoid those pot holes as well.

245/40/20 275/35/20 instead of 245/35/20 275/30/20

Not sure if anyone has done this for long enough to see if it affects the system in at all.

[bimmer_lover_m]

Originally Posted by BlueSander

Got you. Thanks. I'm also toying with the idea of sizing up the sidewall on the 20" set to avoid those pot holes as well.

245/40/20 275/35/20 instead of 245/35/20 275/30/20

Not sure if anyone has done this for long enough to see if it affects the system in at all.

You shouldn't have any problem at all. The diameter is within the 1%. However, it's always recommended to follow the tyre dimensions that you have on your driver's door in order to avoid any issues with the xdrive.