Tire Size & Type Designation

For example the tires on your unit may be marked with a designation of standard trailer (ST) 225/75R15 or light truck (LT) 235/85R16. The designation breakdown is as follows:

  • The first three-digit number gives the width in millimeters of the tire from sidewall edge to sidewall edge. In general, the larger the number, the wider the tire. 
  • The next two-digit number after the "slash" mark, known as the aspect ratio, gives the tire's ratio of the height to width.
  • R - the "R" stands for radial.
  • The last two-digit number is the wheel or rim diameter in inches.