PAX tires are measured in the metric system exclusively unlike the mixed English and metric measurements prevalent in conventional tires. For example a conventional passenger car tire might have the designation 245/45-18, indicating a tread section 245 mm wide, with an aspect ratio of 45% (i.e., the sidewall height is 45% the width of the tread section), mounted on an 18 inch conventional wheel. The similarly sized PAX tire would designated 245-680R460A, indicating the same 245 mm tread section, but a 680 mm overall diameter (a specification not in the conventional passenger car tire nomenclature), the R, meaning radial construction, a 460 mm wheel width (approximately 18.1 inches) and A for asymmetric, meaning that the wheel is asymmetric, or PAX system.
