I'm going to pick up a set of 17x10 wheels at all four corners. Looks like RS-3's (and plenty of other street tires) are offered in 255/40/17. I don't see Hoosier R6's in that size however. They are only available 245/40/17. Hoosier's website recommends a wheel no wider than 9.5" for that tire. Would that be too stretched on a 10" wheel?

They run narrow if memory serves, so yes that would be too narrow, it would under normal circumstances even. Run the 275 in back and if you feel bold try it up front, if memory serves its a shorter tire as well (35 series), so fitment at current ride height would be better over a 255/40 in that regard. Otherwise you will need a stagger with a 9"/245 up front.

255-40 or 265-40

For a 17x10 wheel, you want the 295/35/17 hoosier. I ran that size on my FP car before switching to 16x10s and avon slicks.

Its an option, but a very limited fitment requiring just the right offset, chances are much better on the 275/35/17 I recommended and is a great/more ideal width for a 10" rim.

After further research, Hoosier's website says the section width of the 245 is 10". Which means it's really a cheater 255. This should fit on a 10" wheel.

Whats wrong with you Justin, LOL. a 10 inch rim, 275 and up. I have 255 now on a 9 inch rim.

On a 17x10, the hoosier 295 will be faster than the 275. I have run both, and there is no comparison.

I plan on building the car to TTC spec, so I will be constrained to the 245 (really 255) width tire.