Also, I'm running 19" wheel/tire, everybody say that mpsc 18" is the real deal! and not to be compare to the 19" i been using.

 

R888's are also run on the Speed GT World Challenge series. I don't know of any racing series that runs MPSCs or PCs. From my understanding they (MPSC/PCs) are simply the best "street" tires that perform well on track. R888's are DOT legal, but not considered "street" tires, but more like a "treaded" racing compound tire.

 

World Challenge has a contract with Toyo so they run whatever Toyo provides. Toyo doesn't make an R6, R1, V710 competitor, so they run the RA-1's and now R888. The R888's still haven't even surpassed the former RA-1's in terms of preference for many teams. R888's and MPSC are same concepts from different companies. World Challenge just happens to have a contract with Toyo.

If you watch them rae, you'll see the cars are far more advanced than the tires. World Challenge uses streetable tires to make the cars seem more stockish, but now that they have sequential and stuff, they really need to upgrade the tires. But then they'd need a contract with Hoosier or the like.