it has been 20 years since i bought tires for my pinto .. pretty good mileage i think .. but i want to go with a bit taller tire in the rear and dont remember how to decipher the numbers ,, and i dont remember BF Goodrich tires being so pricy ,, i may look at Cooper Tires as well but anywho i have 225 70R 14 on the rear and want a little bit bigger radius .. what is the 225 or the 70R telling me and what will be a bit larger ..