> Kent brought up a wonderful point in addition, instead of limiting Wheel
> sizes limiting tire sizes. This is not only cost effective for SP
converts, it
> allows more closely controlling the parity and It is safer! I would
rather see a
> 205 tire stretched on a 9" rim then a 315 on an 8" rim.
To be honest, I don't think it's all that much safer. I'd much rather see
people being able to run the design width wheel for their tire. Let's leave
the silly "cram 10lbs of crap into a 5lb bag" stuff for the stock classes.
But you've got another problem to consider here - tire sizes, which is to
say, the section width stamped on the side of the tire, are a fictional
statistic. Not once have I seen a tire's measured section width be the same
as the number on the sidewall - and for that matter, I've yet to see a
tire's spec sheet match the measured dimentions either.
What this means is that all 245's are not created equal. BFG's numbers tend
to run on the narrow side, Kumho's are a lot more generous, and I don't
know about the Hoosiers.
Rim width at least is easily checked, but what do you do if a tire runs a
little wider than the sidewall marking? Or if a sneaky tire company started
making 275s stamped as 245s?
And what do you do if someone brings Mickey Thomson G-15s?
None of these may be killer tomatoes, but these are the sorts of things you
have to consider when writing rules. Be devious! The competitors sure will!
:)
> 3000 + lbs e.g. Corvette 305+
> 2500 + lbs e.g. Z3 1.9/ Rx7tt 245
> 2000 + lbs e.g. Miata 225
> < 2000 lbs e.g. Lotus élan 205
> <= 1000 lbs e.g. lotus 7 185
I think again you're too narrow in the 2500-3000lb space. A lot of
Corvettes came stock with 275 series tires, and you don't want to be in the
position where you require a narrower tire than stock.
I think too that the stock RX7 TT runs a 255 series tire, and they're in
the 2500-3000 range. Once you get below 2500lbs, you kinda fall off my
radar, as all my experience is with heavier cars, but you'll want to find
out about them too. What size tire do the CRXen, the Miatae, and the MR2's
run in Stock class now? Don't go any smaller than that!
So maybe
3000+ 295+
2750 275
2500 255
2250 245
2000 235
1750 225
1500 205
1499- 185
> The only place this gets thrown off are the Hoosier bias ply's they
perform
> like a much larger tire
That's the other thing you have to worry about, much more likely than a
manufacturer purposly mis-labelling tires: compound. A Hoosier today acts
(kinda sorta) like a Kumho one size larger (when hot) because of the
stickier compound - with an attendant tradeoff in life. There's no reason
why a manufacturer couldn't make a set of super-sticky, 3-run tires, that
would blow your carefully determined wheel width/tire width formula into
the weeds. (Although maybe the DOT requirement sets a lower limit on
stickiness - anybody know what a tire must have in order to qualify for a
DOT rating?)
DG
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