Your wheel’s load rating or weight capacity is an extremely important aspect of vehicle safety. The load rating determines how much weight your tyres can safely carry at maximum air pressure. If load rating is ignored, it can result in tyre failure, causing damage to your vehicle or bodily harm to you and your passengers in the event of an accident.
A wheel’s maximum load rating is determined by checking the back of your wheel. To find your wheel load rating requirements, divide your vehicles heaviest gross axle weight rating by 2. Gross axle weight is the actual amount of weight each axle can carry. To find the axle weight rating, look for an identification label on the driver’s side door jamb, gas tank door, glove compartment or truck lid. This label shows your recommended tire size, load rating and tire pressure.
When shopping for a new tyre, if it has a smaller load index than your OEM wheels, DO NOT make the purchase. A tyre with a lower load rating cannot properly support the weight of your vehicle, its passengers and equipment. It will also be incapable of handling the force required for emergency manoeuvres. Inversely, upgrading to a tyre with a larger load rating is ok because it can safely carry more weight capacity.
Overloading a tyre can stress its casing and construction, causing failure or a blowout. Abnormal flexing under heavy loads can cause the edges of the tread to build up excessive heat and begin separating from the tyre. The cords in the sidewalls can also begin to unravel, especially in warmer climates where the roads absorb heat. Once the cords have begun to unravel, they are likely to continue deteriorating, even after the heavy load has been removed.
If you are looking to avoid any weight capacity issues but often carry heavy loads, consider upgrading your vehicle to a truck or larger SUV.