An earlier post recommended reducing your tire pressure for the race. I do not agree with this, but it may depend on the size/type of tire you are running. I usually run my tires at 35 for street, but will go up as high as 50 for autocross. Here's how to tell what pressure you'll need, without getting very technical or requiring additional equipment.
Use some chalk or shoe polish to mark the sidewall of your tire, right up to the shoulder. After your first run, see how the markings have worn off. If it shows that you are rolling the tire over onto the sidewall, increase your pressure. If it shows that you are not anywhere near the sidewall, then you can reduce the pressure. The idea is to use all of the tread surface, without going onto the sidewall.
Good luck, and have a good time.
