Load Range and Load Index

Load Range and Ply Rating

There are a few different classifications tire experts use to discuss a tire’s ability to hold air pressure and carry weight. You’ll find one of these classifications, the load range, listed on the tire sidewall represented by a letter. This letter code gives you a comparative idea of the tire’s toughness; helping you understand how much air your tire can hold, how much weight it can carry, and it provides a relative measure of the tire’s durability. Tires with higher load ranges carry heavier loads.

Load range is based on an older measurement called “ply rating.” All tires are constructed of rubber and cord layers referred to as “plies.” Historically, more plies gave a tire a larger load carrying capacity, so manufacturers would count a tire’s plies and use this number to denote carrying capacity. 

However, a modern tire’s construction uses fewer, stronger plies. Therefore, load range simply defines the tire’s toughness and maximum allowable air pressure, as opposed to specific information about its composition. For example, a “C” load range indicates that a tire is equivalent to a 6-ply construction tire. This tire isn’t actually built of 6 plies, but rather one or two plies of equivalent strength.

When it comes to load range, you may see these indicated as C1 or C2. To simplify this even further, the letter C still indicates the load range but the number after it designates a difference in max load carrying load pressure. For example: C1 and C2 are both 6 ply rated, but C1 has a max of 50 PSI and C2 has a max of 35 PSI. This holds true for other ply ratings too. See chart below.

Check the tire sidewall to find the letter that indicates the load range. Passenger tires are usually unmarked because they have a standard 4-ply rating. However, you may find passenger tires marked as Standard Load (SL) or Extra Load (XL or Reinforced). Both of these types have a 4-ply rating, but the Extra Load can support additional load at up to 42 PSI, as opposed to the Standard Load’s 36 PSI. Some passenger tires indicate higher max air pressures than the Max Load Carrying Load Pressure of the tire in which case a tire expert may need to weigh in and we are always happy to help.

Check our chart to see the load range and ply rating and the max load carrying load pressure.

Load Index and Load Carrying Capacity

Tire experts also use a system called load index to further describe a tire’s carrying capacity. The load index explicitly indicates how much weight a tire can carry. To find your tire’s carrying capacity, look for the load index number on its sidewall.

The load index number indicates a tire’s carrying capacity when inflated to its maximum load sustaining pressure. It corresponds to another number in an index, which tells you how many pounds of weight the tire can carry.

Find your tire’s load-bearing capacity by checking our load index below. Remember that most passenger cars have load index values ranging from 70-110.