Originally Posted by Robbie_B
They're two totally different types of tires. R1's are slicks and NT01's are R-Compounds. NT-01's can handle rain, R1's won't. R1's will have more grip and heat resistance. You can also use Toyo RA-1's. They have the same compound as NT-01's.
Sorry, they are both DOT legal R comps, neither are slicks. The R1's are a bit softer, faster, and naturally don't wear as well.
The NT01's aren't really ok in the rain, whereas the Ra1 is.
So, they are different tires in the sense that the R1 is a bit faster, but they are certainly in the same overall class. An R1 is closer to say a Hoosier or V710 DOT legal tire, than an RA1, NT-01, R888. But they are all DOT legal R-comps none the less.