So I am slowly getting the Boss ready for some track and hillclimb events. I have a set of the AM 18x10 wheels that just went on clearance and was going to get some Hoosiers but saw a post about used slicks. I remember doing business with John Burget back in the early 90's when I last was on the track. Another member got some 305/645/18 slicks that he said were good for several events and cost about $500. That sounds great for my budget but I have never used slicks. I assume the 305 is good for a 10" wheel all square but what about compound choices? The 645 relates to diameter, right? Just want to know what to ask for when I talk to John.