100 for squeals 150 for wheels....mm that is.......if you can,do an equal sub-base, but whacker it, concrete comes in many mixes but a truck is about 6 cube. For any base get the best you can afford at the same time speak too the suppliers(yellow pages) they v, often have overs they need to dump P.M(GMT)..........all the best and dont forget the run off. Always float it and then a polish..........who needs trainspotters?