Three tire maintenance strategies to improve fuel efficiency

The bottom line to fuel economy starts at the bottom of the vehicle—with the tires. One challenge service personnel are faced with is how to provide accurate, meaningful input into the truck order process that will contribute to the company’s bottom line but not add to vehicle complexity. Three areas to focus on are:

• Tire selection
• Alignment
• Tire monitoring systems

Each area is directly related to fuel economy and the key is to understand how each affects dollars spent on fuel. For a deep dive into each, the North American Council for Freight Efficiency (NACFE) provides detailed confidence reports on these and many more topics. Below you'll find some of the key data and learnings from those and strategies to start shedding fuel costs immediately.

Tire selection

Low rolling resistance tires

Industry trends prove that more and more fleets are recognizing that the benefits of low rolling resistance (LRR) tires outweigh the challenges, and that LRR tires represent a good investment for improving fuel economy. However, there are concerns about the reduction in traction and a harsh ride. Fleets operating in northern states with adverse weather conditions have expressed the most concern about traction, and some have adjusted the specifications for trucks operating in those regions. As with any spec change, driver input should always be part of the process. The earlier management fields that feedback, the more successful the transition will be.

Duals or wide-base?

Fleets seeking to improve fuel efficiency through tires should not only consider rolling resistance, but also compare configuration. Would duals or wide-base singles provide the greater benefits?

At one time the benefits of wide-base tires compared to duals included lower rolling resistance, up to 1% reduction in overall vehicle weight, an equivalent upfront purchase price (one wide-base tire cost about the same as a similar pair of dual tires), and the potential for reduced maintenance.

On the other hand, the industry perceives the challenges associated with wide-base tires to include limited product availability, an increased cost of on-road breakdowns, a decrease in resale value, a reduction in the ability to retread the tires, and poor driver acceptance. Additionally, as wide-base tires have low rolling resistance, they face the same concerns around a decrease in traction and tread life as LRR duals. Recently, tire manufacturers have been able to reduce the rolling resistance of duals to nearly match wide-base singles. As a result, the take rate of wide-base singles has declined.

Currently, rolling resistance is not a publicly available data point for tires. Some major tire manufacturers, like Michelin and Goodyear, offer tools for comparing the fuel savings of different tires and brands, but their tools are not comprehensive and it can be hard to make comparisons between options. Fleet evaluations can prove less effective as fleets order new batches of trucks. Because other specs also change, it is nearly impossible to get an apples-to-apples comparison from one tire to another.

Total cost of ownership

Calculating the lifecycle cost of tire ownership is also critical. Traditionally, tire per-mile cost is defined solely in terms of initial purchase price, and as tire replacement may be more frequent with LRR than with non-LRR tires, the value of the LRR options has been underrecognized by the industry. ln fact, the cost of the fuel that a tire consumes due to its rolling resistance is five times greater than the initial purchase price of the tire. Rolling resistance accounts for 30% to 33% of the total fuel cost of a modern, aerodynamic, Class 8 truck, or about $0.012 per mile with dual tires. The typical upfront purchase cost of tires is only $0.04 per mile. But given the range in rolling resistance among dual tires on the market today, tires could be claiming anywhere from $0.14/mile to $0.28/mile in fuel costs. Put simply, fleets that are purchasing tires without considering the fuel expenditure impacts of those tires are going to be miscalculating the impact of their tires on their bottom line.

Wheel alignment

After selecting the correct tires, it’s important to maintain them to maximize fuel efficiency benefits. Precision truck tire alignment systems are required to eliminate tandem scrub and steer axle toe errors that contribute to increased rolling resistance and in turn reduced fuel efficiency. A tire that deviates only 1/4 degree from straight will travel 10 to 15 feet sideways for each mile the vehicle travels forward. Alignment issues may not be visible but still can cause the tires to scrub, increase aerodynamic drag, increase vibration, reduce stability, cause poor handling, and decrease the vehicle’s fuel mileage.

Cummins shared data from tests looking at wheel alignment that resulted in fuel efficiency losses of between 0.6% and 2.2%. Meanwhile fleets that have taken steps to ensure their tractors and trailers are aligned reported to NACFE that they have seen fuel savings in the 3% to 11% range.

Many fleets schedule alignment checks for the tractor at steer tire replacement. Some also have an alignment check as one of the steps in their preventive maintenance inspections, while others have a check connected to total operating mileage of the vehicle. Few fleets reported they had any scheduled checks on trailer wheel alignment.

It seems that trailer alignment is checked only following driver complaints. Fleets also say that improper alignment that can cause either well aligned tractors and trailers or those with alignment problems, to be worse after an alignment. It is, therefore, extremely important to be sure that fleets are using a robust the alignment process.