>How about this all numbers are MAX size tires with standard SP wheel
>allowances
>
> > 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
>There are, however, some pitfalls:
>
>1) SM is based on the SP rules, and the SP rules say "any width wheel" Not
>only would you have to write a new rule to close the loophole, I'd really
>hate to see a SP-transplant get saddled with all his existing wheels now
>illegal. Shades of Prepared!
I agree that tire size is a better way to limit, because 1) it's easier to
police (quick visual) and 2) the SP guys like me (BSP Vette) don't have to
go buy new rims (as was said above). However, just from a quick look, a 305
limit for the big cars is kind of an odd way to go simply because I don't
think anyone's making a 305/xx 17 right now. Most all of the BSP vettes out
there are running 315/35 17's. I know Hoosier only makes the 305 for the
18" wheel.
>2) You have to do your homework, because in no case should any car's Stock
>wheels be illegal as shipped. Probably not a problem in Miata-space, but
>I'd bet there's a few Corvettes in the 2700lb range with factory 9" (or
>better) wheels.
Z06's have 17x9.5" front and 18x10.5" rear. Standard C5's are 17x8" (8.5"?)
front and 18x9.5" rear
>3) Bring car weight into a classing proposal at your peril. Once you have
>weights on the books, that means you need to start weighing cars in
>impound. That adds a ton of administrative overhead to a class, and you
>want to avoid that if at all possible.
If you want to avoid the weight issue, but also not have gutted "street
cars" out there, require that things such as factory sound insulation and
carpet remain in the car. That's the bulk of the dieting right there.
>This I can help with. You allow:
>
>- 2 seats, normal SM limits or displacement/induction
>- 4 seat, "sports car based" (from SM exclusion list) with normal SM limits
>on displacement/induction
>- 4 seat, SM-legal, any displacement/induction, all other SM rules apply
>
>What I want to do is send you the 383 Camaros and the Vortech 5.0 Mustangs,
>so I can get performance data on them to see if they can be brought into SM
>without tipping the balance. I rather suspect I can, but I need data first.
Sounds good except for one thing...Seeing as how the big-inch cars are
American V-8's, would it be so bad as to allow the NA displacement to be set
at a given CID, preferably ~390. This allows the Chevy's to run 383's (and
still have room for a rebuild, as a 0.030" over 383 is a 388) and allows the
Fords to run a 351-based 377 stroker. Yes, there are far more 383's running
around than 377 Fords, but the popularity of the 377 Ford is growing (though
not as fast as the 347).
>I think you're too narrow in the 2500-3000 lb range. Getting a Corvette
>sub-3000 isn't all that tough, and stock Corvette tires are 275s, with a
>design rim width of 9.5" (and I think they'll fit 12" without much
>trouble!) And make no mistake, a BIG chunk of your participation pool is
>Corvettes.
All true. Most BSP guys run 17x11's all around (yes, 11's in front too),
and some of the C5 guys (and maybe a few random C4's) are running 17x12's.
And yes, they do fit.
>3000+ 10"+
>2750 9.5"
>2500 9"
>2250 8"
>2000 7"
>1500 6"
>1499- 5"
>
>After all, what you really are after here is to put the light cars on
>skinnier wheels, because small+light is a much bigger bonus than lots of
>power. Once you hit 2500 or so, large changes in tire width pay much, much
>smaller dividends than at lighter weights, and it stops mattering so much.
You make some sense here, but your list shows a steady 1" width increase per
500 lbs through the entire list. This doesn't follow with what you said
about the increased width mattering less at higher weights. I still go by
my earlier statement that I feel that policing tire sizes is a MUCH better
way to handle that issue.
John Gross
1987 BSP Vette "currently sick"
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