Im gonna chime in here, and don't want to spread undue stress, cos I had the same query a while back having different brand/tread tires front and rear and was specifically told that the actual tread pattern had to be the same rear and front or you risk transfer case issues...be good to finally know the truth here

I'm not sure if anyone has suggested that tread patterns make any difference or can put your transfer case in peril but (just like the old saying), size certainly matters, at least in terms of matching the rolling circumference front to back.

Hey Wpoll hope all well, it was to do with the traction control side of things and that one axle could possibly be overworking to compensate for the difference in tread/surface are contact with the road leading to " the issue" dunno will dig up the old post if i can , sure its here...

I guess that's possible but isn't that what xDrive does - varying the drive to each wheel depending on the traction available? ;)

I'd be VERY surprised in all the other variables (gravel on the side of the road, mud, snow etc.) we not a greater factors than the very slight difference in traction a different tread pattern would make. :dunno:

All good here - getting ready for winter and lower traction.... :rolleyes:

Yeah you are right come to think of it.....tire place i went to a while back was adamant that i would f up the transfer case running different fronts to rears....
we are getting ready for summer.....come early its 30C today pile of dust and sorry to hijack this post..ps if i find the replies i got re the trans.case i'll add em

here is my old post and some replies

https://xoutpost.com/bmw-sav-forums/...g-trouble.html

I believe that the 2004+ xdrive only engages a clutch back in the center differential which sends torque to the front wheels when the rears are slipping. I think it may selectively brake individual wheels but I doubt it does that except in heavy cornering. Saying it "sends torque selectively to each wheel" is not untrue, but it's not a particularly accurate statement either. Either way, unless you are driving very aggressively or driving on a slippery surface such as ice or gravel, I doubt it is doing much.



But to answer the question about tread, the tread pattern shouldn't matter at all UNLESS the tires have worn differently such that the circumference changes. If you put an aggressive summer tire on the front, and a crappy 100k-mile all season on the rear, not only with the front be much stickier (which is dangerous) but it will also wear out much faster, and after putting some miles on, the difference may be enough to start making your center diff unhappy. The treadwear rating should be similar or the same if you are going to do this, unless it's just for a short time.



Like I said in your old post, omodos, putting stickier tires on one axle than on the other can tend to be dangerous, and should only be done with caution.

Even with DSC to control wheel slip there is good reason to keep the more grippy tires on the rear axle.

I don't believe different tread being a problem for x-drive for a minute.

You can always actually measure the tire circumference with a tape measure turned inside out. Mark the overlap with tape and read where tape is. Rolling circumference will be a little different I think that's part of why BMW specs 39psi back when loaded.

1200/32=37.5 in.² front and 1600/39=41 in.² contact patch for my car

If I had 32 in the back: 1600/32=50 that will for sure mean different rolling circumference.

01 e53 doesn't care about these things all open dif and must take more wheel to wheel difference to care.

X-drive From my understanding and the feedback from driving at 328xi Is that the front axle is completely disengaged when you’re not moving and after the launch it kicks in the front drive but it always kicks on some amount it doesn’t die wait until their slippage. I think the ratio is roughly 2/3 back 1/3 front. X Dr. can put 100% of the torque to a single wheel by locking the slipping wheels with the brakes.

I’m about to test drive 50i x5 and and I’m really hoping that I can’t feel the front axle kick in like the 328.

Returning from tangent: If you wanna compare your rolling circumference squeeze a piece of crayon Into the trade of the front and a back tire and dryer’s and then measure the distance between the two marks

appreciate all feedback and sorry jumped in post.....so rolling circumference is key and ideally similiar 'type' summer all round or mud and snow all round....PS NOV 2004 x5 3.0d, i dont think has x-drive , all the notes you mention still apply to non xdrive

Good man much appreciated clarification.....