I ordered a set of the Falken's this morning for my project (275 and 315). Interestingly, the guy I ordered from said that they only had 4 of the 315's in their warehouse, and he didn't have any more on order. Given that they auto-restock them, he suggested that perhaps Falken was out of stock at the moment (a guess, but it makes sense).
So while I could have gone with a slightly wider tire, I think these are going to be a good fit for my project to get it on the road and track.