Car tires have three numbers that list what size they are, with the first being width, the second being sidewall aspect ratio, and the third being the diameter of the rim. Find out what dimensions are used to measure tire sizes with help from car restoration specialists in this free video on car maintenance. Expert: Gary Malec & John Grassi Bio: Gary Malec and John Grassi rebuild cars and boats, do household handyman work, and build computers. Filmmaker: gary malec