Thread: 22's on a 650
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Old 04-07-2011, 10:19 PM
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Yorgi Yorgi is offline
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Location: Toronto
 
Join Date: Mar 2005
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Mein Auto: '04 M3 / '06 650i Cab
If you guys are rubbing on the bottom spring perch then you probably need a spacer. The important measurement between the different tire sizes is the radius. A 1" increase in radius = 1" closer to the spring perch.

Stock 245/40R19 = 13.35"
235/30R22 = 13.77" (+3.05%)
245/30R22 = 13.89" (+3.86%)
255/30R22 = 14.01" (+4.68%)
295/25R22 = 13.90" (+3.93%)

I went out to measure and found my OEM 19" stock ellipsoids have about 1" clearance between the top of the tire and the bottom of the perch. Increase in radius for stock vs 255/30R22 is 0.66" so in theory there should be plenty of room.

The spring perch is slanted though, so the closer to the strut you go the less clearance there is. If you are rubbing due to high offset wheels a spacer will give you more clearance to the strut and the bottom of the spring perch.

On a side note, I included the diameter % increase in brackets. Even if the 255/30R22 fit they are 4.68% larger than stock which is far beyond the recommended 3% max increase in diameter.
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Last edited by Yorgi; 04-07-2011 at 10:22 PM.
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