In the case of light truck tires

As previously explained, most light truck tires follow the alpha-numeric tire code indicated by the letters LT at the beginning of the size code. However some light truck tires use a High Flotation code, indicated by the letters LT at the end instead of the tire size or simply omit the LT code completely as follows:

• The tire diameter is given for High Flotation tires and omitted from Numeric tires.
• 2 digit number: The diameter of the tire in inches
• x: Separator character.
• 3 or 4 digit number: The section width (cross section) of the tire in inches. If the tire diameter is not given, section widths ending in zero (e.g., 7.00 or 10.50) indicate the aspect ratio is 92%, while section widths not ending in zero (e.g., 7.05 or 10.55) indicate the aspect ratio is 82%.
• Construction of the fabric of the tire:
  • B: bias belt (where the sidewalls are the same material as the tread, leading to a rigid ride)
  • D: diagonal
  • R: radial
• 2 digit number: Diameter in inches of the wheel rim that this tire is designed to fit.
• LT: Designates that this is a Light Truck tire.
• Load index and speed rating are not required for this type of tire but may be provided by the manufacturer.
• 2 or 3 digit number: Load Index
• 1 or 2 digit/letter combo: Speed Ratings.
• Additional marks: Tire Markings.

Example: Tire labeled: 37X12.5R17LT

• 37 - the tire is 37 in (940 mm) in diameter
• 12.5 - the tire has a cross section of 12.5 in (320 mm)
• R - this is a radial tire
• 17 - this tire fits 17 in (430 mm) wheels
• LT - this is a light truck tire.