Every tire has a load rating that specifies the maximum weight it can safely support when properly inflated. This isn't an arbitrary number but rather an engineering limit that directly affects your safety. Exceeding a tire's load rating leads to excessive heat buildup, structural stress, and dramatically increased risk of tire failure. For vehicles that tow, haul, or carry heavy loads, understanding load ratings is absolutely essential.
The load index is a numerical code found on the tire sidewall as part of the service description, the numbers that follow the tire size. For example, in a tire marked 265/70R17 115T, the 115 is the load index and the T is the speed rating. The load index corresponds to a specific weight capacity from a standardized table. A load index of 115 means each tire supports up to 2,679 pounds. Multiply by four for the vehicle's total tire-supported weight: 10,716 pounds. The load index ranges from 70 (up to 739 pounds per tire) for small car tires to 126 or higher (over 3,700 pounds per tire) for heavy-duty truck tires.
Light truck tires add another layer with load range designations, expressed as letters from C through F. These correspond to the number of ply equivalents in the tire's construction and determine the tire's inflation and load capacity. Load Range C tires are common on lighter trucks and SUVs, while Load Range E tires are designed for heavy-duty applications like one-ton trucks and vehicles that regularly tow heavy trailers. Moving from Load Range C to Load Range E on the same tire size significantly increases weight capacity but also results in a firmer ride due to the stiffer sidewall construction.
Choosing the right load rating requires knowing your vehicle's gross vehicle weight rating (GVWR), which is the maximum total weight the vehicle can carry including the vehicle itself, passengers, cargo, and trailer tongue weight. Your tire's combined load capacity should always meet or exceed the GVWR. This information is on the same door placard as your recommended tire pressure. When replacing tires, never downgrade to a lower load rating than what came on the vehicle from the factory. This is especially critical for trucks and SUVs used for towing, where the additional weight of a trailer tongue and cargo can quickly approach load limits.
Many drivers don't realize that load ratings and tire pressure are interconnected. A tire's load rating is valid only at its maximum specified inflation pressure. Running lower pressure reduces the effective load capacity. This is why maintaining proper inflation is especially important for trucks, SUVs, and any vehicle that carries heavy loads. When shopping for tires on Ship.Tires, the load index is clearly listed for every tire to help you make the right choice. If you're unsure which load rating you need, refer to your vehicle's original tire specifications as your baseline and never go below them.