Any tire used on U.S. highways/streets should have a DOT (Department of Transportation) mark. The DOT symbol certifies that the tire is compliant with the U.S. Department of Transportation’s safety standards.

According to DOT regulations, Tire Identification Numbers (TIN) must begin with the letters DOT, followed by eight to 13 characters. The DOT information often identifies the manufacturing location by a code, tire size code and type code, followed by the week and year the tire was manufactured. DOT also requires the date code information to be marked on intended outboard sidewall (certain exceptions apply).

The DOT code identified here is FDAPLJO4518. The first two letters, FD, identify where the tire was produced. The next two letters – AP – are known as the size code. The next three letters, LJO, are type code and 4518 is the DOT date code of the tire. According to the DOT, the FD code assigned here is for the Yokohama Factory in Japan. The AP identifies the size and 4518 identifies that the tire was built in week 45 of 2018.

Highway tires, which are marked DOT, should pass all the requirements on the FMVSS No. 139 laboratory testing for radial tires on light vehicles. This applies to all new pneumatic radial tires for use on motor vehicles (other than motorcycles and low-speed vehicles) that have a gross vehicle weight rating (GVWR) of 10,000 pounds or less and were manufactured after 1975.

FMVSS 139 testing includes tire-marking, tread wear indicator, tire dimensions, tubeless tire bead unseating resistance, tire strength (plunger), tire endurance, low-inflation performance and high-speed performance. A DOT tire must pass all the tests before being released to the market.