Commercial dealers tell MTD that their customers are becoming more conscious of fuel efficiency. The Tire Retread & Repair Information Bureau (TRIB) has a lot to say about rolling resistance and some of the other factors than can influence fuel economy.
1. A 10 psi drop in inflation pressure can reduce fuel mileage by 1%; 15% under-inflation can reduce miles per gallon by up to 2.5%.
2. Other factors that affect fuel efficiency and miles per gallon:
* alignment: out-of-alignment conditions can stack up and result in up to a 2% loss in fuel mileage;
* temperature: tires will lose 1 to 2 psi for every 10-degree change in temperature. Always gauge tires cold. The normal air pressure build-up due to operation/service conditions will be 10 to 15 psi in a radial truck tire;
* speed: for every 1 mph increase in speed over 55 mph, miles per gallon is reduced by about 2%. Some 45% of the fuel efficiency of a tire may be lost when a tire runs at 75 mph instead of 55 mph;
* traffic/driving habits: regardless of transmission type, frequent stops and starts should be avoided where possible. Every stop and acceleration with a full load costs between .2 and .3 gallons of fuel. For those fleets that are equipped with manual transmissions, drivers should be encouraged to get to the highest gear possible without running engine rpm up to rated speed in each gear. Trucks are typically spec’d so that desired road speed can be achieved with engines operating between peak torque rpm and rated engine speed. Engine manufacturers provide driver training to help fleets optimize drivability as well as fuel efficiency;
* loads: for each 10,00-lb. increase in load, fuel economy will drop .5%;
* idling: consumes .5 gallon/hour without air conditioning. Air conditioning increases fuel consumption by .4 gallon/hour. If you are stopped more than five minutes, shut the engine off.
To learn what else TRIB has to say about rolling resistance and fuel economy, see the June 2014 issue of Modern Tire Dealer, or check out the digital edition, where we outline the truck tire market with the help of three commercial dealers.