I have a race this coming weekend in SC. and I have a set of Dunlop D952's on right now and they are still good (knobs arent worn much) The track Iam going to be at is all sand and I was wondering if I should put 756's on the front and back or just leave the 952's on? The 756's I have are about half worn but I took a dremel tool to the knobs and squared the edges back on to make them grab better. What do you guys think I should do? I dont want to buy another set of tires right now with just two races left this season. They will be going on my 06 yz450f with 47 hours on it now.