ba-autox
[Top] [All Lists]

Re: M3 tire question

To: Jerry Mouton <jerry@moutons.org>
Subject: Re: M3 tire question
From: "John J. Stimson-III" <john@idsfa.net>
Date: Thu, 26 Apr 2001 14:57:46 -0700
> I thought I'd mention that I believe that based on the
> stock class rules, it's not necessary to go with the same
> stagger front to rear that the car came with.  The rules
> allow ANY wheel of a size near what was shipped with the car,
> and it's not in the class of "a complete option set", as the
> rule allows wheels that are not of the exact same size, even,
> that was offered on the car.

I can see where you're coming from -- that would be pretty cool,
because then I could run 15" wheels on my 2001 Miata LS.

Here are the relevant sections (from your web site, of course!):

----
Option package conversions may be performed between specific vehicles
of a particular make and model, but only between configurations from
within a particular model year. Such conversions must be totally
complete and the resultant car must meet all requirements of this
section.

13.4 Wheels
Any type wheel may be used provided it complies with the following: it
is the same width and diameter as standard, and as installed
(including wheel spacers if applicable) it does not have an offset
more than +/- 0.25 inch from a standard wheel for the car. The
resultant change in track dimensions is allowed. Vehicles originally
equipped only with 12 inch diameter wheels, may use 13 inch diameter
wheels of the same width as standard and offset within +/- 0.25 inch
of standard.

Vehicles equipped with rims having metric specifications may use
alternate rims as determined by using the following procedure.
    Diameter: converting the metric measurement to inches and using
    the nearest smaller inch diameter rim.
    Width: converting the metric measurement to inches and using the
    nearest smaller 1/2-inch width rim. Offset and track must still
    comply with the requirements of this section.

12.4 Standard Part
An item of standard or optional equipment that could have been ordered
with the car, installed on the factory production line, and delivered
through a dealer in the United States. Dealer-installed options or
deletions, except as required by factory directives, no matter how
common or what their origin, are not included in this definition. This
definition does not allow the updating or backdating of parts.

----

I can see how you could interpret "same width and diameter as
standard" by looking at the definition of "standard" and seeing that
it's any part that could be ordered with the car.  

However, under the suspension section, it says that "standard springs
must be used".  If you used the same reasoning, Miatas (for example)
could mix and match springs between the R package and standard
suspension.  So just as you must observe the package conversion rule
with springs, you have to observe the package conversion rule with
wheels (as I interpret it).  If wheel size is an option which is
independent of any other package, then you can of course use any of
those wheel sizes.

The definition of "standard part" does specify that it does not allow
updating/backdating, but doesn't explicitly address package
conversion, which leaves some ambiguity.

Surely this has come up at National events before!  How has it been
interpreted in the past?

-- 

john@idsfa.net                                              John Stimson
http://www.idsfa.net/~john/                              HMC Physics '94

<Prev in Thread] Current Thread [Next in Thread>