RE: ASC vs Tire size, was Early vs. Later E36 M3

[Dan Hermann <dahermann@xxxxxxxxxxxx>]

>I modified the setup on my 98 E36 M3 to be that of the
>95 M3 - 235/40-17 on 17x8 on all corners. (Helps with
>understeer and turnin). I have not noticed any ASC
>kickin up to approx 100MPH. I have measured about a 2%
>difference in true speed vs indicated now (the speedo
>says 61 MPH at a true 60 MPH). Question is: normal
>tire diameter differences between manufacturers can
>easily produce this variation, it would be BAD for ASC
>to kick in at highway speed due to normal tire
>variation or slightly modified setup (such as mine).
>Do you know what the threshold for detecting wheelspin
>with ASC is? Is there a speed on the highway I should
>no exceed without ASC off?

i've also changed the wheels/tires on my 96 M3 to 17x8" for 
my track wheels and 18x8" for my street wheels.  i've not 
experienced ASC intervention at any speed up to an 
indicated 135mph.  i know lots of people in my situation as 
well that have had no ASC problems.  when changing wheels, 
most everyone retains the rolling radius of the stock 
wheels (within +/- 3% or so) so i do not believe that a 
difference in wheel speed would result from the wheel/tire 
changes.  it's only the width of the wheel/tire or the 
profile of the tire that changes.  i don't see how that 
would affect ASC nor do i see how speed could exacerbate 
the problem.  i don't think you have to worry about 
unexpected ASC intervention.

regards,

dan
96 M3 (ASC only off on track)
88 325is (ASC only as good as lump in driver's seat)

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End of bmw-digest V9 #2034
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