With Fuel Costs on the Rise, Tires Play Important Role For Fleets

With diesel prices continuing to escalate to close to $4 per gallon this month, this is a great opportunity to talk about the impact of tires on fuel economy.

The unrest in the Middle East is not going to end any time soon. Diesel prices will only get worse as we head into the spring and summer months. This is not a good scenario for keeping the number one fleet operating cost – fuel – in check.
If a fleet runs tires that are 10% underinflated, it will cost about 1% in fuel economy; 20% low pressure equates to about a 2.5% drop in fuel efficiency; and tires that are 30% underinflated will cause a 4% or more loss in vehicle fuel economy.
The second highest operating cost next to fuel is tires, so now is a good time to review what your commercial fleet customers require to keep their tire program costs from going off the charts. As a tire dealer, it’s also the perfect time to work with your fleets so they understand how they can maximize vehicle fuel economy.

There are many factors that affect fuel economy:
• Vehicle configuration
• Route
• Loads
• Vehicle aerodynamics
• Driver
• Tires/Retreads

A tire dealer can play a significant role in maximizing a fleet’s tire costs (and help with fuel costs) by assisting the fleet in choosing the specific new tire and retread combination that will achieve the best fuel economy with minimal effect on traction and mileage.

While there is usually a small trade-off, tire fuel economy can be effectively improved without reducing traction and mileage.

Every tire company offers a line of “fuel economy” tires. You must first understand all of the design variations between the “regular” tire and the “fuel efficient” tire. And, of course, the more fuel efficient tire typically comes with a higher price tag.

A fleet may currently spec a drive tire design with 28/32-inch of tread. A similar fuel-efficient version may be only 26/32-inch deep. Why the lower initial tread depth? The answer is heat. The deeper the tread depth, the hotter the running temperature. A lower tread depth design will run cooler and, as a result, can improve fuel economy. Keeping a tire running cool during its entire life can only improve the fuel economy picture.

A specific tread pattern also will have an effect on tire fuel economy. The more “open” tread designs are great for traction but not as good for fuel efficiency. A tread pattern with solid shoulders will always be better for fuel economy, but traction may take a hit.

Then there is the tire design variable that you just don’t see – materials. A tire rubber compounder has a plethora of materials from which to choose when designing a tire. Select-ing materials that run cooler will help in fuel economy.

Let’s take a closer look at tread rubber. Using as much natural rubber as possible will keep the tire running very cool. Synthetic rubber runs a lot hotter than natural rubber, hurting the fuel story. A fleet sees a tire as black and round, it doesn’t “see” NR or synthetic, and no tire databook addresses the difference. So it is important that the dealer explain the basic compound differences with the more expensive fuel economy version.

It normally is an easy sell to fleets to convince them to purchase the more expensive fuel efficient tire design. Fleets understand it is all about cost per mile, not initial buying price. Increasing fuel economy by 1% or 2% equates to a much shorter ROI vs. losing a few thousand removal miles because of the lower initial tread depth of the “fuel economy” tire.

Maximizing Returns
A fleet can go out and spend more money on the fuel-efficient tire design, but it all goes to waste if the tire is not run at the correct operating pressure all the time.

This is where the driver effect on fuel economy also comes into play. If a driver or service tech doesn’t check tire pressures on a regular basis, the tire footprint increases dramatically. More rubber on the road increases rolling resistance, reducing fuel economy.

A typical radial 295/75R22.5 tire with 100 psi has a tire footprint (contact patch) about 7 inches long. When that same tire is running at 70 psi (30% underinflated) the footprint length increases to 8.25 inches. That is 18% more rubber on the road. There is a direct correlation between the amount of rubber on the road and fuel economy.

Maintaining proper tire pressure is critical and is the key factor in maximizing fuel economy. Numerous industry studies all show the same result: if you run 10% underinflated, it will cost you about 1% in fuel economy, 20% low pressure equates to about a 2.5% drop in fuel efficiency, and if you are 30% underinflated, you are looking at a 4% or more loss in vehicle fuel economy.

A common scenario, especially on trailers, is to have the outside dual tire at 100 psi while the inside dual is 70 psi. This will even magnify the drop in fuel economy, since the tire with 70 psi has a different number of revolutions per mile vs. the 100 psi tire. The result is that irregular wear will develop very quickly and when you have a tire with shoulder cupping instead of smooth, even wear, the fuel economy gets worse.

So why do tires even lose air to begin with? There are actually three primary reasons:

• Osmosis through the tire casing (1-4 psi per month depending on specific make/model)
• Tread area punctures (2-3 psi or more per day)
• Valve core/stem

The question is how often should you be checking a fleet’s tire pressures? Every day, every week, every month, or only during preventive maintenance?
The answer is that it depends. A driver can take the time to check every tire before leaving in the morning, but one can run over a nail at any time – even when just leaving the yard.

And even then, when the driver or service tech does check tires, they need to be using a calibrated tire pressure gauge.

With the high price of fuel, this is also a good opportunity to visit your fleets and conduct a meeting with their vehicle maintenance teams. Include drivers and the techs. Talk about how important it is to keep tires running cool to maximize fuel efficiency.

Talk about those things that cause a tire to run hot. Low tire air pressures, driving too fast and running a high load are the worst combination, and surely will adversely affect vehicle fuel economy. And talk about the other factors impacted by hot tires, like belt edge problems that will prevent retreading.

This type of educational meeting with commercial fleets will go a long way and is a win-win, making your commercial dealership even more valuable to your customers.