[Gustavz973]

ok guys so I got my hands on some f10 wheels they are 18x8 Et 30 but i used two different size tires for front and back

i did 225/40/18 on the front and 245/40/18 on the back but im getting problems with the dsc, when i hit certain bumps it vibrates and then the dsc light comes on, is this because Im staggered, it didnt do it before with the oem wheels....

Any feedback is appreciated..

[Longdoggy]

Yea man. Its the stagger, or better yet the roll out. What will determine your staggered compatibility is the roll out calculation of your tires. They need to exact/as close as possible else your front and rear axles will turn at a minimally different rate which is likely to cause trouble with your tranny.

I've done your calculations for you on what you own and the measurements on the tire itself and you have a 2.4% difference in tire size which is significant.

You can do more measurements here: http://tire-size-conversion.com/tire-size-calculator/

This will help you determine what size tires to use so that you can get the same/similar roll out for both front and rear.

[Greyfox]

That tool will get you in the ballpark, but you need specifics from the tire manufacturer to be exact.

But yes, your stagger is way off....

The rolling circumference of a....

225/40/18 is 1945mm
245/40/18 is 1990mm

So your rear tires are trying to travel 50mm more than your front tires each revolution. Since they are basically locked together by the transfer case you can see why you have a problem.

[stashtrey]

Run squared or you'll destroy your tcase and/or differential(s)!

Don't drive it anymore until you match front/rear tires or get your rear tires under 1% rolling diameter difference.

I run 235/40/18 F and 265/35/18 rear.

Since you have squared rims you should stick to squared tires.

[firemanjust1]

Do not drive car like this at all , +1 on destroying parts and very costly fix .

[ctuna]

Go to the xi sub forum
I think its possible to run staggered widths but not diameters.
Though I wouldn't do it .

[Delta0311]

With 225/40/18 front the rear should be 255/35/18

[Delta0311]

Corrections your fronts should be 225/45/18.
And yes you can run staggered if your xi came with 18s then they are staggered

[Nati0n]

Staggered width is not an issue but the front to rear rolling diameters must be within a certain tolerance, on 4-Matic it's 1/10th of an inch front to rear not sure what it is on xDrive. The major risk is wearing on your transfer case or differentials because of increased heat due to the improper ratios. If it is causing issues with DSC rarely I doubt it's an issue, but over EVERY bump and turn it is probably worth changing them.

Since you did the same sidewall ratio for front and rear on different widths I can already tell you the sizing is wrong. Generally you want (once again speaking on my 4-Matic and general tire knowledge) a difference of 40mm front to rear (245/285, 255/295) and a sidewall aspect ratio difference of 5 (225/40 and 265/35).

But as everyone said above your best bet is to go calculate out your rolling diameters as they can vary per tire brand too.

Best of luck

[MonacoBlueE90]

Originally Posted by Gustavz973

ok guys so I got my hands on some f10 wheels they are 18x8 Et 30 but i used two different size tires for front and back

I know i said at that other thread that use 255/35/18 rear tyre, but since your wheels aren't staggered and 8 wide is little bit narrow for 255/35/18 wide go with 225/40/18 or 235/40/18 front and rear. Your current tyre combo is really bad for xdrive.

Originally Posted by Delta0311

Corrections your fronts should be 225/45/18.

No 225/40/18 is the correct size for e90's.

Originally Posted by Longdoggy

You can do more measurements here: http://tire-size-conversion.com/tire-size-calculator/

We have our own calculator also http://www.e90post.com/forums/forumdisplay.php?f=12

Originally Posted by ctuna

Go to the xi sub forum
I think its possible to run staggered widths but not diameters.
Though I wouldn't do it .

Yes it is possible here are few 18 inch staggered tyre combos that work with xdrive. These all are under the 1% difference.

215/40/18 front 245/35/18 rear
225/40/18 front 255/35/18 rear
225/40/18 front 265/35/18 rear
235/40/18 front 265/35/18 rear
235/40/18 front 275/35/18 rear

[AndreyT]

Any references to "ruining your differential" while running staggered front-rear setup in xi car are nonsensical. Modern BMW xi AWD system does not have center differential, so obviously it can't get ruined.

BMW xi is an electronically controlled "wet clutch pack" design. It is true that putting staggered wheels on this system (outside of acceptable tolerances) can lead to unjustified activation of the clutch and premature wear or overheating of the system. However, as far as I know, this system can be programmed for each specific front-rear wheel diameter difference, if you really want a staggered setup on an xi car. Albeit I don't remember ever seeing it done in USA.

[Ph0zenstone]

Originally Posted by AndreyT

Any references to "ruining your differential" while running staggered front-rear setup in xi car are nonsensical. Modern BMW xi AWD system does not have center differential, so obviously it can't get ruined.

BMW xi is an electronically controlled "wet clutch pack" design. It is true that putting staggered wheels on this system (outside of acceptable tolerances) can lead to unjustified activation of the clutch and premature wear or overheating of the system. However, as far as I know, this system can be programmed for each specific front-rear wheel diameter difference, if you really want a staggered setup on an xi car. Albeit I don't remember ever seeing it done in USA.

This post is nonsensical

[gtaccord]

Actually just the pure physics of the system will not allow for the a front tire that is smaller than the rear without some problems "programming" or not. With a slightly smaller diameter front tire (< 1%) you will get surging and some drive ability issues/annoyances. With a drastically smaller diameter front tire (> 1%) you will definitely have major problems and error lights. Basically you have to keep the front tires the same or larger diameter within 1%. Wheel and tire width does not have any effect on the system.

[Greyfox]

Originally Posted by AndreyT

Any references to "ruining your differential" while running staggered front-rear setup in xi car are nonsensical. Modern BMW xi AWD system does not have center differential, so obviously it can't get ruined.

BMW xi is an electronically controlled "wet clutch pack" design. It is true that putting staggered wheels on this system (outside of acceptable tolerances) can lead to unjustified activation of the clutch and premature wear or overheating of the system. However, as far as I know, this system can be programmed for each specific front-rear wheel diameter difference, if you really want a staggered setup on an xi car. Albeit I don't remember ever seeing it done in USA.

You can not program a differential to turn faster on the front output than what the engine input is providing and the rear output is sending to the rear wheels. That is something that takes gears, not clutches.

[v1nc86]

Oem 18" wheels on my '08 335xi came with 225/40-18 front and 255/35-18 rear.

[gtaccord]

Originally Posted by v1nc86

Oem 18" wheels on my '08 335xi came with 235/40-18 front and 255/35-18 rear.

From BMW??

Factory tire size is 225/40 front and 255/35 rear. It did not come from BMW with 235/40s in the front.

[JaysBlueE92]

Yikes so much poor information here. The xi can handle staggered widths, as others have said the key is to be within that 1% rolling diameter. Stay away from mixing and matching brands

[v1nc86]

Originally Posted by gtaccord

From BMW??

Factory tire size is 225/40 front and 255/35 rear. It did not come from BMW with 235/40s in the front.

Typo.

225/40-18 front and 255/35-18 rear

[stashtrey]

Originally Posted by AndreyT

Any references to "ruining your differential" while running staggered front-rear setup in xi car are nonsensical. Modern BMW xi AWD system does not have center differential, so obviously it can't get ruined.

DO NOT LISTEN TO THIS PERSON.

Irresponsible post, dude. You should take I down since you clearly don't know what you're talking about. Reread your post. Are you on salvia?

[Delta0311]

Please ignore my post on the fronts I made a mistake as someone else pointed out.
Optimal tire size for 18s on a xi staggered is
(as stated in the manual and the setup I have)
Front 225/40/18
Rear 255/35/18

[MGT81]

Originally Posted by Delta0311

With 225/40/18 front the rear should be 255/35/18

Yup. I have staggered TSWs on my XI. Original tire sizes (225/255). 18 inch wheels, 8 in width front and 9.5 inch rear. Never had a problem.

[AndreyT]

Originally Posted by stashtrey

Irresponsible post, dude. You should take I down since you clearly don't know what you're talking about. Reread your post. Are you on salvia?

One more time: what I said above is basic factual truth known for anyone who has any idea of what BMW xi AWD is. Moreover, this is not exactly trade secret of any kind. Get some Reading and Comprehension 101 classes, then do some reading on the subject. Once you do I might even allow you to pass judgement about my statements from time to time.

That applies to any other "mechanical genius" here who managed to "discover" a center differential in BMW xi AWD.