235/55R17 99H- The load index (99) is the tire size's assigned numerical value used to compare relative load carrying capabilities. The higher the tire's load index number, the greater its load carrying capacity.

97 = 1,609 pounds

98 = 1,653 pounds

99 = 1,709 pounds

A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original and should not be considered for installation on the vehicle.

Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 130.