Some have successfully mounted 285/30-18s on stock 8" rim. Why isn't this the tire size of choice on a B-Stock RX8 ??? Seems like everyone is running 245s?

 

Because the fast tire, Kumho V710, in a 285 wont fit on an 8" wheel. Only the slower tires will fit.

 

Lol ...

 

710s wont mount but Tim Pryor tried that 2 years ago with the Hoosier. The 285-30-18 A3S04 fit on the Stock rims but rubbed on the the rear.

 

Who are some?

 

they only rubbed in the rear because the wheel was the wrong offset

there's no point in running a 285 on an 8" wheel, but go ahead and try ...

 

245-255 is the most contact patch you are going to get out of an 8" rim... even if you can fit a bigger tire on there.

I'm suprised you didn't see the 12 other threads about this before buying your tire.

I say cut your losses and buy an 18X9.5" rim asap... and kiss B Stock goodbye.

 

Contact patch is highly dependent on tire construction. 275 Hoosiers work well because of the their cantilevered sidewall. They just weren't as fast as 710s. But now with the A6 out we've got to relook at it. I've got a set on order. Should have some info after May 7th.

 

LOL, I'd be inclined to test/run the 225/40 before the 275/35, but thats my whacky way ...

 

Don't understand why when we had data showing the 275 S04s were faster than the 245s on 8 inch rims.

 

wish you the best then