Tires play a critical role in improving mileage
By Don Darden
Fuel consumption and improved efficiency is on the mind of every bus and coach operator. What perceptive owners quickly learn is that poor fuel economy leaves room to parlay small and seemingly unrelated steps into significant fuel mileage improvements.
Where does the fuel go?
Due to energy losses in the engine and drivetrain, only about half of the burned fuel actually moves the vehicle down the road. Here are six factors that drain fuel usage of its full benefit:
1. Driving habits — Excessive speed is the biggest factor in reduced mileage. Careless driving habits lead to poor fuel economy. Running at high speeds on intercity bus routes guzzles fuel. So do jackrabbit starts and hammer-down runs between stops in city driving, which also burn out brakes. Driver education and incentives can be very effective in reducing fuel consumption.
2. Tire alignment — The tires must point straight ahead in order to roll with the least possible resistance. Misaligned tires scrub as they turn. This scrubbing can cut tire life by as much as 20 percent.
What’s more, an axle misalignment of just 2.5 degrees can cause enough drag to increase fuel consumption by 16 percent. This is all easily corrected with an effective vehicle maintenance program.
3. Vehicle aerodynamics — Buses and motorcoaches are not the most aerodynamic vehicles on the highway. Fuel consumption lost to wind resistance only worsens at higher speeds.
At 55 mph about half of the fuel turning the wheels is consumed by the bus just pushing against the oncoming air. At 65 mph the bus is eating up nearly two-thirds of the available fuel energy. Any measure taken to improve performance against aerodynamics and wind resistance will pay off in fuel savings.
4. Vehicle maintenance — Alignment isn’t the only vehicle maintenance item that affects fuel economy. Check and maintain fluid levels and replace filters regularly. Repair any fuel or fluid leaks promptly. Keep careful maintenance and mileage records.
5. Tire maintenance — Proper inflation is vital to maintain proper stress distribution and to reduce the flexing and heat build-up that wastes fuel.
Heat build-up causes tires to wear faster and accelerates the aging process. Improper inflation reduces the traction, making tires a safety hazard. Under-inflation wastes fuel, wearing out tires prematurely and reducing their capability for retreading.
Regardless of the tires in use, maintaining correct inflation pressure will optimize tire performance, tire life and fuel economy.
Inflation pressure effect on fuel economy — Bridgestone Mileage Sales recommends a program to reduce all of these losses by ensuring proper tire inflation.
Check and adjust inflation pressure regularly; when the vehicle has been parked at least three hours and before it has been driven more than one mile. Adjust inflation pressures to meet vehicle and tire requirements.
6. Select fuel-efficient tires and retreads — Tires manufactured especially for buses can improve fuel consumption. Choose from a wide variety of low-rolling resistance new tires and retreads designed to save fuel.