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Tire Sizes

    Scott:
    
    Welcome back to the BMW crowd.
    
    I computed the rolling diameter and wheel-revs/mile based on my (not 
    completely forgotten yet) school geometry.
    
    I know there is also a computer program somewhere on the internet to do 
    the computation.  But if you have any basic calculator, use the 
    formulas below:
    
    If a tire specs (in current standard denomination) are WDT/ASR-WHS
    
    Where:
    
    	  WDT = Thread width (in milimeters)
    	  ASR = Aspect Ratio (in nn)
    	  WHS = Wheel size (in inches)
     
    then:
    
    Rolling Diameter = 3.14159  x  [(WDT x ASR) + WHS] 
     (in inches)		     ---------
    	  			       1270
    
    and
    
    	  		   63360
    Wheel-revs/mile =	------------
    	  		Rolling Diam.
    
    
    For 195/65-14, these numbers come out at 75.336 in. and 841.0
    
    
    P.S.:  I just made up these formulas and it's late at night.....  So it 
    would be preferable if somebody could confirm them (or check them 
    against the computer program).
    
    P.P.S.:  Scott: Are you sure you do not want to trade your new-used 
    1990 325i E30 for my still torque-challenged 1985 318i E30 ?  Mine may 
    be a nicer color :-)