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
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
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