Most of us never stop to think about the maximum load our tires can support. After all, passenger cars are usually used to transport well...passengers, and any human beings who would cause the vehicle to exceed its maximum load are unlikely to fit through the car doors in the first place. But (and just like in the example above it's a big butt) with the large number of light trucks, SUVs, and vans being used as primary transportation today, a tire's maximum load becomes a much bigger factor. There will always be at least one, and possibly two, indicators of a tire's maximum load printed right on the side wall. The first is the Load Index. This is a numerical code ranging from 74 to 111. This number doesn't tell you much, and sometimes it will be completely absent. Luckily it doesn't matter. The Load Index is more for tire professionals than for the average person who wants to know if carting around a piano is going to cause a blowout. The information you want to look for is the Maximum Load. This will usually be right beside the Load Index and will read, for example, MAX. LOAD 875 kg (1929 lb.). This seems simple enough, right? Too bad this number is actually misleading. If you continue to read along the sidewall, you will find an entry that says something like AT 35 PSI MAX. PRESS. Problems can arise because this number is very often different than the vehicle manufacturer's recommended maximum tire pressure. This information can usually be found on the door post or inside the glove box. If in doubt, your vehicle's manual will have it for sure. According to tire manufacturers, you should always follow the recommendations of the vehicle's manufacturer, regardless of whether the tire itself can handle a few more pounds of pressure. The maximum load carrying capacity of the most tires is rated as either Standard Load or Extra Load. Standard Load tires are limited by the load that can be carried with a maximum inflation pressure of 35 psi. The same goes for Extra Load tires; however, the maximum inflation pressure is 41 psi. If you're not sure what type of tire you have, check the sidewall. If you see either 'XL', 'Reinforced' or, simplest of all 'Extra Load' then you have Extra Load tires. Standard Load tires are well...standard. Therefore they do not have any special identification. Some Standard Load tires are branded with a maximum inflation of 44 psi. This is an indication that the tire is designed to meet special performance requirements. It in no way increases the tire's maximum load. No matter what kind of tires you have, a little foresight and common sense can save you from having to buy new tires too soon, or worse, a catastrophic accident. Loading a quarter-ton pick-up truck with half a ton of concrete is simply asking for trouble. Even if the tires can take it, sometimes the vehicle can't. |
