Selecting the correct tire for a trailer helps prevent blowouts from the tires being overloaded, decreasing the risk of losing control of the trailer while driving. Trailer tire manufacturers have introduced the same descriptive coding system used for truck and passenger cars, making it easier to read trailer tire load codes. All tires now use the same tire load index system to indicate their capacity. They also use the same size, rim and speed code indexes as well.
Find the trailer tire description code. It will be written on the side wall of the tire (i.e. ST195/60R15 87M) or included in the description of the tire.
Identify the load portion of the code. It will be the last two numbers followed by a letter (i.e. 87M). The numbers are the load index and the letter is the speed rating for the tire.
Find the load index number on a tire load index chart. Read the corresponding weight limit. For example, a tire with a load index of 87 has a weight capacity of 1,168 lbs.
