Originally Posted by CanAutM3
They are far from identical.
I was told both use the same (or very similar) rubber compound, but the thread patterns and tire structures are very different. The NT01s are designed for heavier cars, with much bigger thread blocks and a stiffer carcass compared to the RA1s.
This is also true for the NT01s, I have run corded tires for several sessions and still had plenty of grip
I should have clarified...I meant compound not construction. The RA1's came with 8/32 and should be shaved for dry use on a heavy car. The NT01's are good from sticker.