[Batman]

If you are racing on street tires at 40 PSI and 20 PSI you are asking for trouble, they aren't designed like that. Drop the fronts down to the recommended tire pressure (I think 32PSI?) and if you are going to deflate the rears don't go below 26-28 PSI. You probably won't gainmuch at all by deflating street tires, they aren't designed fpr low pressure running. In a worst case scenario you could lose the bead at that low pressure and possibly have the tire fall off the rim.