Significance

The load rating of a tire is based on its range and index. The range of a tire identifies its strength and ability to maintain air pressure, and the index refers to the actual weight the tire is designed to carry.

Function of Load Range

The tire load range is identified alphabetically. The stronger the tires, the further along in the alphabet the load range letter will be. For example, heavy load tires are branded XL. However most passenger-vehicle tires that feature a standard load range are not branded on the side of the tire.

Function of Load Index

The tire's load index is represented by a number, usually from 70 to 100. The higher the tire's load index, the more weight it can safely carry.

Identification

For example, in the tire size P195/60R15 87S branded on the side wall of a tire, the "87" is the load index. In the tire size, "P285/35R-19 LL," the "LL" is the load range. In the first example, since no load range is given, it is assumed that the tire has a standard load range.

Expert Insight

Before tire load ratings were used to indicate the strength and weight carrying ability, the tire-ply rating was used that indicated the actual number of body ply layers built into the inside of the tire.

Source:

Tire Rack Tech Load Index

Tire Rack Tech Load Range