Increasing fuel prices are not only taking their toll at the pump, they are affecting tire prices as well since oil is a major ingredient in the manufacture of all tires.
One simple and immediate way for owners and drivers of commercial vehicles to make the most of their fuel and tire money is to pay greater attention to proper tire maintenance. This is critical for new and retreaded tires alike, asserts David Kolman, Associate Director of the Tire Retread Information Bureau (TRIB).
TRIB is a non-profit, member-supported industry association dedicated to the recycling of tires through retreading and proper tire repairing and maintenance.
Air pressure is at the heart of proper tire maintenance, Kolman points out. By maintaining the proper inflation pressure for a given size of tire and load, tires will provide the best fuel mileage and safety, while minimizing wear and maximizing retreadability.
Commercial tire manufacturers have tables and charts - available free for the asking - that specify air pressure adjustments for tire size, load and speed.
It is the air inside the tire that carries the weight of a vehicle, not the tire, explains Kolman. The air supports the weight, absorbs shock and keeps the tire in its proper shape so it may perform as designed. The tire serves as the container for the air.
In addition to affecting rolling resistance and thus fuel economy, inflation pressure also influences handling, traction, braking and load carrying capability.
Improperly inflated tires have an uneven, irregular and inconsistent tire footprint (that portion that contacts the road surface). Because the tire doesn't roll as smoothly or as easily as it was designed to, fuel efficiency declines, as the engine has to work harder to keep the truck moving.
Tires are made of layers of fabric and steel cords encased in rubber. Tires flex when they roll, which bends these components.
Underinflation is a major contributor to premature tire problems because underinflated tires cause excessive flexing which generates heat, and heat is a tire’s worst enemy, says Kolman. There is a direct correlation between how much a tire is underinflated and how much faster it wears.
Underinflated tires tend to run hotter, diminishing retreadability. “This is significant,” he notes, because retreaded tires provide the same dependable performance and safety record as new tires but at a far lower cost - as much as 50% less. Retreads deliver the best possible return on tire investments.”
Particular attention needs to be paid to tire pressure in mated dual tire and wheel assemblies. Inflation mismatches on these tires can cause tire diameters to differ enough that the larger tire will drag the smaller tire. This results in rapid and irregular wear, especially on the smaller tire.
Tire pressure should always be checked when a tire is cold,” advises Kolman. That is before a vehicle has been driven or driven less than one mile. Once a vehicle has been driven, tires warm up and experience an increase in air pressure and that causes an inaccurate reading.
TRIB’s recommendation is that tire pressure be checked regularly, at least once a week, and always with a properly calibrated tire gauge. “Inflation pressure cannot be accurately estimated by kicking or thumping the tire,” Kolman stresses. “Trying to determine if tires need air by thumping them is as effective as trying to determine if the vehicle’s engine needs oil by thumping on the hood.”
It only takes about 20 minutes to check and adjust inflation pressure on an 18-wheel tractor-trailer, says Kolman. “That is a small investment once a week to get better fuel efficiency, longer tread life and improved retreadability - all of which help lower operating costs.”
Kolman also recommends the dirty hand test at least once a week. Truckers are encouraged to rub their hands over their tires to determine if there are any abnormalities. By catching a problem early a tire can often be repaired resulting in a large dollar saving, plus a time consuming, expensive tire problem on the highway might be avoided.
Kolman recommends installing value caps on all valve stems and keeping them tight to seal against valve leaks and to keep out dirt and water. Metal value caps are best as they contain a rubber gasket to provide an airtight seal. Most plastic caps do not.
Even well maintained tires lose air pressure, on average about one or two pounds per month. This is a natural occurrence as air permeates through rubber.
Several things that can be done to help maintain proper tire inflation, Kolman notes. One is to fill tires with nitrogen instead of compressed air.
Nitrogen allows a tire to retain more of its original properties so there is less inflation pressure loss for a more stable and consistent tire pressure, longer tread life and less oxidation of tire components. This assists in increasing tire life, improving fuel economy and reducing tire aging for a more durable casing for more retreadability.
Another option is the use of various tire pressure monitoring and control systems. Some warn of low pressure. Others equalize air pressure for slow leaks. Still others help maintain air in a tire that is damaged, enabling the driver to get to a repair facility.
There are additional benefits to properly maintaining tires besides maximizing fuel economy. By being more fuel efficient, less fuel is consumed. This saves money at the pump, decreases petroleum fuels demand and reduces emissions and pollution.
Along with lasting longer, tires that are well maintained have improved retreadability, which conserves natural resources and helps the environment by reducing solid waste disposal problems. For every retread produced, one less new tire needs to be manufactured.
Because every reputable truck and bus tire manufacturer designs and engineers its tires for several retreading lives, only one worn tire casing requires disposal instead of many, observes Kolman. The natural resources that are saved and the positive impact on the environment are multiplied.
So are the cost benefits to users of retreaded tries. “For most commercial vehicle fleets, tires represent the third largest item in their operating budget after labor and fuel costs,” he says. “Retreading can cut tire costs by up to 50%.”
To learn more, contact the Tire Retread Information Bureau toll free from anywhere in North America at (888) 473-8732 or by e-mail at [email protected] TRIB’s web site - www.retread.org - contains a huge amount of valuable information and resources about retreading, as well as on tire maintenance and tire repairing.