This screen from the Racer's Leading Edge Tire Bank program shows where you would enter the tire information for each tire/wheel combination for your car.  Your can have up to 15 tires.  Suggest you mark each wheel with a number from 1 to 99.  This matches the Tire ID from TR01 to TR99.  Then carefully measure the tire circumference (distance around center of tread in inches) and enter into program.  This tire information is used for your selection in the Track Setup and Chassis Weight Setup.   When Edit is selected, a popup screen allows you to Add a new tire, update tire information or delete a tire from the Tire Bank.

Note: While measuring tire circumference, all tires should have the same tire pressure to have consistent measurements.