They are GRP Rally Tires. Get em on Ebay (I did) or GRPGandini site.
+1 on the 8ight. But I would add a L8ight Bumper, and an 8ight-T chassis. They will all bolt right on. just need center CVs. With buggy arms, Truggy length chassis, Slammed like a L8ight (with wedge type body); Castle 1520 - 8s on the New MMMXL. I see 110+ mph easy...
Buy em quick!!
http://cgi.ebay.com/GRP-GM01C-D1C-Ra...item5adcf6d5e4
Edit: I just noticed they have the Sweet Spoked rims too! Lucky!