you have to look up the tire's specs, and what the manufacturer says the tire will do in terms of revolutions per mile.. its not as simple as calculating the circumference and dividing that by a mile.. the tire deforms as you drive at different speeds.. most if not all manufacturers should have that on their websites
2003 3.8L V6 4R70W
Windstar Upper Intake with cool-air intake, MAC LT headers, BBK O/R H-pipe, and flow 40s, SCT tuner, FRPP Alum. D/S, 3.73 gears, Auburn HP limited slip, and Team Z LCAs, Eibach sway bars.
Best 1/4 time: 15.036 @90.92mph, 2.148 60'