LT (light truck tire)

How to read it

The federal standard defines a light truck (LT) tire as one designated by its manufacturer as primarily intended for use on lightweight trucks or multipurpose passenger vehicles (FMVSS 139). Ford’s manual describes LT as a Tire and Rim Association designation for tires intended for service on light trucks, and Yokohama as a light truck-metric size designed for pickup trucks, which carry more cargo and tow more than passenger cars. In LT245/75R16 the letters come first; in older flotation sizes such as 35x12.50R17LT they come at the end (Yokohama). An LT tire also carries a Load range (LOAD RANGE E) letter, which FMVSS 139 requires on its sidewall, and often two load indexes separated by a slash, such as 120/116.

Also searched as: LT in tire size, LT tire.

Single and dual loads

The two numbers are for the tire used singly and as a dual, side by side on a rear axle. NHTSA defines dual use as four tires on each rear axle, six or more on the vehicle. USTMA’s example sidewall reads Max Load Single 1380 kg (3042 lbs) at 550 kPa (80 psi) Cold and Max Load Dual 1260 kg (2778 lbs) at 550 kPa (80 psi) Cold. Pirelli says the dual rating is usually lower to cover a tire in the pair failing and the other carrying the full load. Yokohama’s example, 121/118, is 3,197 lb single and 2,910 lb dual.

How LT tires differ from P tires

Michelin describes an LT tire as having a stiffer carcass and higher load capacity, for towing and heavy payloads. The federal rules show the difference in load: on a truck or multipurpose vehicle, FMVSS 110 counts a passenger car tire’s load rating only after dividing it by 1.10, and an LT tire’s in full. They also run at higher pressures. In its high speed test, FMVSS 139 inflates a standard load passenger tire to 220 kPa, and LT tires of load range C, D and E to 320, 410 and 500 kPa.

Standards and grades

LT tires with a tread depth of 18/32 inch (about 14 mm) or more are covered by FMVSS 119, the standard for heavy vehicle tires, instead of FMVSS 139. Ford’s manual notes that the federal quality grades (treadwear, traction and temperature) do not apply to LT tires.