Quote:
Originally Posted by brad850csi
Quote:
Originally Posted by Miko M
265 front and 285 back is 2.6%. NOT 2.3%
Didn't know we have that size, all I know is 275 front and 285 back which is 1.1 %
Bmw recommendation is 1.3% or less
Obviously less is better.
Rim width doesn't effect the rolling diameter much but, you can't stretch the tire to much.
This is old article from BMW :
"The tire circumference can fluctuate up to 1% or more as a result of mixed tires or wear. The tire tolerance logic decides depending on the driver's command and driving situation whether the slip is to occur in the transfer case clutch or at the contact area between tire and road.
If the slip is permitted in the transfer case clutch, the locking pressure set by the pre-con- trol is reduced in order to keep the work loss low. In the driving dynamic control situation, the clutch is locked slightly more than normal, the four wheel drive is always guaranteed when required.
For maximum xDrive performance, tires (and wheels) of the same diameter should be installed on the vehicle."
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Here is where the 265 and 285 combo is documented:
https://www.realoem.com/bmw/enUS/sho...diagId=36_2297
I was doing 27.98" / 27.35" = 1.023035 for the 265 and 285 option
Then for my 21" concept, 28.21" / 27.58" = 1.022843 |
Looking at the website on mine phone it looks like 265 or 285 not 265/285 unless I am seeing things different. Need to go on computer and look at the website.
Your first option would be acceptable, second one IMO not so much.
Any AWD manufacturers ( like Subaru ) don't recommend to go over 1% they are pioneers in AWD
I personally like to stay below 1.3% to be safe