Hi gene , a 235/70/15 tire is 27.95 inches in diameter, 722 revs/mile.

A 225/70/15 tire is 27.4 inches in diameter, 736 revs/mile.

So 14 more or less revolutions in one mile, 14 revs x 15 miles = 210 revs in 15 miles.

One revolution is 27.4 inches, 27.4 ... Login to read more.