A helmet Snell rated SA/M 2005 or better is required.
June in Wisconsin, the weather can be anything from rain and lows of 40 to highs of 90. Most of the Paved Paddock at Road America is up on a hill open to the wind from almost any direction. Bring a selection of garments, both heavy and medium weight water proof jackets, and sweat shirts.
As the rules state you and or any passengers will need long pants,long sleeve shirts,as well as closed toe shoes. As you inspect or work on your car you may get dirty so bringing a spare set of clothes to the track is a good idea.
Do not put new street tires on the car you may ruin them! The deeper tread will flex and the tread blocks will roll over under heavy cornering. This may cause the tire to chunk,ie lose whole tread blocks or sections of the tire tread. A partially worn street or competition tire will perform more consistently and wear less because they have been heat cycled. Heat cycling makes the tire more resistant to wear.
Use a Z rated or higher tire if you are driving a high performance car. Check your tire pressure several times during the day to insure that the tire is properly inflated. There is an air station at the gas pumps at Road America.
Slicks either new or used are acceptable.However we encourage their use only by experienced drivers. Their handling and traction characteristics are quite different than a DOT rated street legal tire. Learn to drive on used street tires for the first two years, get to know what the car feels like at speed. Then when you put on slicks you can truly enjoy the performance difference.
This is just a starter list. A lot depends on your cargo capacity.Most things are available in the area or can be borrowed from your fellow entrants.