Tires on Trucks
Adequate tires on heavy trucks are essential to assure the consistent and safe operation of heavy trucks, to prevent the need for emergency handling procedures due to tire blow-outs, and to minimize damage from wear and tear on roadways. Advocates support requirements to upgrade the quality and reliability of truck tires (e.g., carcass design and tread depth) to improve skid resistance, stopping performance and fuel efficiency per payload, to mitigate damage to highway pavement and to assure the optimal performance of antilock brake systems.
Tires, like most manufactured products, are designed to operate within a specific load; we call this tire load rating. On the sidewall of your trucks tires you will find a rating for a single application and a dual tire rating (usually the drive wheels).
Each rating is accompanied by an inflation pressure that, if used, will give you the stated rating. This does not mean that this inflation pressure is correct for your truck. Trucks can be loaded in various ways, inflation pressure must be set based on the load being carried by the tire, if you wish to achieve optimum life and performance from you tires.
Every tire manufacturer publishes load/inflation tables for their products, which provides us with this critical information. Also, remember that the specified pressures are cold pressures; in other words, pressure in the tires before the tires start rolling down the road and heat becomes involved.
If the load on a tire is greater than the maximum rating shown on the sidewall, you must correct the situation. This can be done by reducing the load on the tire, either by unloading or redistribution of load. This can also be done by upgrading to tires with a higher load capacity.
Tires come in many different load ranges, so it may be possible to change to a higher-load-rated tire within the same size. If you do so, be sure not to exceed the load rating of the wheel. If you change tire sizes, make sure you consult an industry expert to ensure that proper fit and vehicle compatibility are maintained. Keep in mind that installing tires with a higher carrying capacity solves only the problem of tire overload. It does not increase the gross axle weight rating, and does not resolve issues related to the overloading of other components — axles, suspension components, etc.
Reading inflation tables
Be certain that you have the correct load/inflation table for the manufacturer of your tire. Different tire manufacturers use different specifications. On the table, find the load you measured on the applicable line, dual or single, and move up to the corresponding MINIMUM inflation pressure for that load. Since inflation tables give us the MINIMUM pressure to carry the load, it is suggested that you move one block to the right on the chart to give yourself a safety margin. If you find that your load exceeds the chart rating, address the cause. Do not try to compensate by straining the capacity of your tires.