A car is traveling at 50 mph. Find the revolutions per minute of the wheels if the car tires have a 26 inch diameter.

50 mph , 13 inch radius

50 mph(5280ft in a mile)/60 min an hour = 4400 ft/min

total distance in 1 minute ---------------^

13 inches/12 inches in a foot * 2pi = 13pi/6 <--- 1 revolution

4400 ft/min / 13pi/6 = 646.41 rev per min

646.41 revolutions per minute? Did I do that right? Thank you for your help in advance.