MUST SHIP UPS GROUND - BITE!!! Not a softener. You need to be careful with this product as too much will lock you down. This prep works great on Maxxis EL tires to get them the bite you want. The original application requires at least 8 days to work into the tire and THE TIRES MUST BE SCUFFED OR SANDED TO REMOVE THE OUTER "SKIN" FOR BEST RESULTS. Generally, high grip kart tires such as HT's, Firestones, and Vegas will get locked down with this prep unless your track is very slick. DIRT STOCK CAR RACERS USE A LOT OF THIS STUFF!!! For Maxxis EL tires at the track, mix 1 part of SST5 Purple with 4 parts Xylene.