Hopefully we get some class shuffle going on. We only have 4 drivers in BSP right now and that includes my codriver.

 

Can you explain this a bit more? I'm not sure I follow this, but I'm very curious.

 

...and was already full when you posted. I'll be there co-driving an A-Stock Solstice. Hopefully I can keep up with those damn rally cars with their damn launch advantage...

 

basically if you check the specs for the 275 tire, tirerack recommends a 10" rim. If you mount a tire on a smaller than recommended rim width, then you squish the sidewalls enough to pull the edges of the tread off the road.



Now imagine what would happen to that tire pictured in the graphic if you were to pinch the sidewalls.. the edges of the tread are raised, much like over inflating a tire reducing the surface area of the contact patch.

http://www.tirerack.com/tires-techpage-1/10.shtml

I compensate to some degree by running lower presures, but by doing so, I take away the ability to adjust my setup with tire presures.

 

So what if you run a 10 or 10.5" wheel with the 275's? How much difference then would there be from a 285 on a 10 or 10.5" wheel??

It would be really interesting to test/data log a 2800# EVO on 275/35/18's vs. a 3000# EVO on 285/30/18's . . .

 

If you have a DL1 and buy some 275's I'll swap you some data.

I'd bet the 2800# car is faster even with the small tires.

 

On that Solstice I'm driving we ran both 275/35 and 295/30 Hoosiers last year. There wasn't much difference. I'm guessing the 275/35 with a 200 lb weight advantage is much faster.

 

I'll continue to run the 275/40-17s, but there's no way my car will approach 2800#. It weighed 3038 @ the Tour...

The sunroof may have to go

 

guys what is your suggestion fro 18-9" 35 off set with 15 mm spacers. if i would like to use the Toyo R888 or the R1R? wich size would be the best for that? I like the 255-35-18, but if you guys have a better idea, would help me alot.
Thanks.

/for road racing/

 

Or you can do what I did last year - buy a sun roof delete kit for my '04 with SSL.

I think the dealership had it listed under "2006 EVO RS" or something like that. Pretty cool, the kit included a new motor, new driveline, and even a sweet aluminum roof!! It is pretty reasonable - only cost me $29000

 

Was that on stock width rims? If so, I would not expect to see any difference.

Now if you put the 270 on a 10" wide rim and the 295 on an 11" wide rim then you will probably see a difference. . .

GriceIX, I think the best way to test it will be to run a 2800# car on the 275's, then add a 200# passenger (or 200# worth of sand bags) and run on the 285's. That would be the best back to back comparison to eliminate any driver or car set-up differences.

What that means is if that new proposal passes then competitors will have to spend the $$$ to drop 200# from their car to test it with the smaller tires, then if that way is slower they will have to put it back up to regular weight . . . seems like a potentially expensive rule to me. . .

 

Robevo, remember that this thread is specifically for discussing the Street Modified SCCA Auto-X class, not random stuff about tires and racing. You could probably make a new thread and get some good feedback on this question.

 

thanks.

 

Whatta bah-gain!

 

I don't know. but I would be very interested in finding out. Lightweight 17x10 114.5 that fit an evo are kind of hard to find. but in anycase, I am keeping a casual eye open for a set that won't totally melt my credit card.

Also, I wouldn't be so bummed out about all the money spent on weight reduction. You can add the weight back in with ballast which could give you a perfect 50/50 weight distribution, matching the BMW in that area. If these rules are implemented, that is my plan.