Low Rolling Resistance Tires: Are they worth it?
It comes with no surprise that tires have a significant impact on not only fuel efficiency but overall fleet costs as well. In fact, tire rolling resistance is the third biggest impactor of fuel economy (behind engine inefficiency and aerodynamic drag). It accounts for approximately one third of total fuel costs, which is normally a fleet’s biggest non-salary operating expense. With that, even the slightest improvement can lead to large sums of savings for the fleet overall. So, on the surface, a Low Rolling Resistant (LRR) tire appears to be an easy choice in increasing fuel efficiency. However, there are tradeoffs that make the decision a little less binary.
First, let us explore the how these tires help fuel efficiency, and then we will examine the return on investment for them.
Factors in Rolling Resistance
Tire rolling resistance means essentially what it says: the amount of resistance tires have against rolling along a surface. Everything has friction, and tires on roads are no exception. There are two main factors that affect the rolling resistance: the tire and the surface. Since fleet managers only have control over the tires, fuel efficiency and cost results vary depending on the driving environment. Looking at the tires, there are a few key factors that affect the rolling resistance.
The number one, most important factor that affects rolling resistance is the tire air pressure. To see how impactful it is, imagine kicking a flat soccer ball through the grass versus a properly inflated one. The flat ball creates more drag against the surface, making it not go as far with the same kick. So, the flat ball would require a harder kick (or more fuel) to cover the same ground as the properly inflated one. Having properly pressurized tires is not only vitally important, but likewise one of the simplest things to monitor and maintain.
The tire’s tread also heavily impacts its rolling resistance. The tire’s tread can account for up to half of the tire’s rolling resistance in many cases, according to Goodyear’s commercial technology director, Mahesh Kavaturu. Think of all the bumps and loose rocks and other things that are on roads. Good tire tread helps grip the road regardless of what is on it and helps not waste as much fuel as well.
The actual compounds/materials that make up the tire affect its rolling resistance. The way these compounds are tested for their rolling resistance is by measuring their “rebound.” Think of dropping a basketball and measuring how high it “rebounds” back up. The closer it gets to the height it was dropped from, the less energy that is lost on its impact with the surface, equating a good rebound metric. So, compounds that have a high rebound also exhibit lower rolling resistance.
Low Rolling Resistance Magic
The magic behind low resistance tires resides in optimizing the tread and tire compounds. In terms of tread optimization, LRR tires work by reducing the tread block’s height, using higher angle drafts to stabilize the tread elements, having the tread elements take more rigid shapes, or by increasing the surface area of the tread block to increase its stiffness. All these actions help make the tire roll over surfaces without as much push back. However, for actions such as reducing the tread block’s height (making shallower tread ridges), it comes at a cost of grip to the surface, which is very important for fleet safety.
Next, in terms of compounds/materials, constant optimization of material rebound assists in the selection process for material used. As LRR tires continue to become more popular, too, the materials are becoming better at lowering rolling resistance while not sacrificing other qualities such as tread life and depth.
LRR tires can help reduce fuel costs by a great deal. These tires—assuming controlled surfaces—can provide between 6-14% better fuel economy than regular tires. This improvement is tremendous when considering trucks on average travel over 100,000 miles per year. A study from the North American Council for Freight Efficiency (NACFE) showed that a fleet could save $7,396 annually per truck on fuel costs with switching to LRR tires. That figure was based on a $2.89/gallon price for diesel (national average). Today, though, diesel prices are $3.15/gallon, which would make the total savings even more. That means that even with a 10-truck fleet, over $75,000 annually could be saved on fuel costs by switching to LRR tires. With 100 trucks, $750,000. Beyond money too, the improved fuel efficiency makes LRR tires a “greener” tire, something very important to the U.S. Environmental Protection Agency, who promotes the use of LRR tires as part of their SmartWay program.
Are LRR Tires Worth it?
With the incredible fuel efficiency savings that LRR tires offer, investing in them would be a no brainer, right? Well, not entirely. First, they are more expensive tires. But more importantly, they have a lower usage life than regular tires by a significant amount. Since the tread is not as deep, less material can be worn off before the tire’s tread is absent. On certain roads and in certain environments, this can sometimes make LRR tires not profitable. Likewise, LRR tires can lead to more breakdowns, increased downtimes, and higher tire costs altogether because they sacrifice key longevity qualities like tread life and road grip.
So, to ensure that LRR tires bring fleets maximum return and minimal loss, close monitoring and routine care is necessary. Using telematics technologies like those offered by EZ Fleet Tracking, fleet managers can set up a consistent maintenance schedule and align tire repairs/replacements with them. Likewise, telematics can bring the added security of real-time notification during possible breakdowns to keep their drivers safe. Another key to helping LRR tires last longer is using fuel-efficient re-treads. These can bring back the tread to the tire without having to replace the entire tire.
Overall, closely monitoring your fleet, and being acutely aware of your needs/environment play the most important role in determining the value of LRR tires. Having a good understanding of the wear and tear of what your current tires go through (and their resulting usage life) as well as the miles you cover will be the best indicators of whether LRR tires can significantly help.