Rolling Resistance

Q: What does rolling resistance have to do with fuel economy?

A: Rolling resistance is a measure of the force required to turn the tire under load. Since the energy to turn the tire must come from fuel, rolling resistance is related to the amount of fuel a truck uses. more information click here.

Q: Why don’t all tire companies publish rolling resistance information for fleets and dealers to use?

A: Partly because there are no universally agreed-upon standards for evaluating rolling resistance. And, because rolling resistance changes with speed and load, the numbers might be difficult to interpret. more information click here.

Vehicle Spec’ing

Q: We have both delivery trucks and line haul trucks. The trucks are spec’d the same. Why is the fuel economy so much better on the line haul trucks?

A: Chances are, your delivery trucks do a lot more starting, stopping, maneuvering and idling. Your line haul trucks may spend most of their time on interstate highways at steady speeds. Going in a straight line at a near-constant speed takes far less fuel. more information click here.

Q: We have a group of vehicles spec’d identically, but their mpg’s are very different. Why?

A: The chart of TMC findings shows some of the variables involved. If the vehicles have different routes or loads, that could account for the difference. Driver skill can also have a huge (up to 35 percent) effect on fuel economy. more information click here.

Q: What are the benefits of on-dash MPG displays in trucks?

A: They give drivers instant feedback on the effect of driving style on fuel consumption, so they can make continual improvement in their driving techniques. more information click here.

Q: Which is better for fuel efficiency, dual assemblies on drives and trailers—or wide base tires?

A: If you can use them, wide base radials offer significant fuel economy benefits over dual fitments. Wide base radials weigh less than duals, there are half as many sidewalls flexing, and there is less wheel and tire weight. There are also many other non-fuel-efficiency benefits. more information click here.

Tire Selection

Q: How can I choose the best tire, when some advertise fuel efficiency while others promise long mileage or traction?

A: Obviously, you’ll want to make sure you have good traction. Driver complaints about “walking” (a sensation that the vehicle is slipping sideways) or about difficulty stopping on wet roads may help you determine which tires are better for you. Then, test tires for yourself. Instead of measuring just fuel economy, calculate total tire cost per mile over useful life. Ask your tire supplier or Bridgestone representative for help. more information click here.

Q: Are all rib tires more fuel-efficient than deep lug tires on
drive axles?

A: As a general rule, rib tires are more fuel-efficient than deep lug tires, if the tires are otherwise identical. Nevertheless, deep lug tires are available today with fuel-efficient designs, and in some instances, these may be more fuel-efficient than some rib designs.

Tire-Related Fuel Economy

Q: When we bought new tires for one of our trucks, the mpg of that truck went down. Why is that?

A: Most tires are more fuel-efficient when they are partially worn. So, if you were close to wearout with your old tires, they probably were delivering better fuel economy than the new ones. more information click here.

Q: How can we improve the fuel economy of our tires?

A: Keep running the tires you currently have installed. As the tread wears, fuel efficiency will improve, regardless of the type of tires you use. And, make sure you have the right inflation pressure for tire and load. more information click here.

Q: With tires advertised as “fuel-efficient,” we noticed a slight improvement in mpg. If we change our speed from 60 mph to 75 mph, will fuel economy suffer as a result?

A: Tests show that your mpg will probably be cut upwards of 30 percent by increasing speed 15 mph. And, you’ll probably lose nearly half the fuel-efficiency benefit the tires provide.

Fuel Economy Testing

Q: We ran a fuel test that showed substantial differences between different tires. When we switched to the more fuel-efficient tires, we could not find anywhere near that amount of savings in our fuel bill. Why?

A: If you ran what is called a “coast-down” test, chances are, the test itself is inaccurate. If you ran an SAE or TMC test, you probably had much greater control over variables than you do in your daily operations. In general, Bridgestone has found the amount of savings you’ll see in the real world is usually half (or less) than what you found in controlled testing.

Q: An SAE-type fuel economy test showed a significant difference in the fuel economy among tires, but a later test showed a much smaller difference. What happened?

A: You probably ran your first fuel test on new tires. The rolling resistance of a tire changes a great deal as it wears. And, the difference between tires usually becomes smaller with wear. The true comparison should be the average difference in fuel consumption over the entire life of the tire. This is usually less than half the difference between new tires. more information click here.

Traction & Fuel Economy

Q: We tried F.E. tires and the drivers reported a loss of traction.
Is this compromise necessary?

A: It depends on the technology used to reduce rolling resistance. In general, natural rubber compounds have lower rolling resistance—but poorer traction—especially in the wet. Newer synthetic rubber compounds also have lower rolling resistance—but a good level of traction.