With commercial trucks, it is crucial to have maximum vehicular efficiency on every route. To that end, each tire must be appropriately aligned and able to experience unobstructed, resistance-free movement. Unfortunately, opposing factors to this movement do exist that drivers are often unaware of.
What Is Rolling Resistance?
Rolling resistance is the anti-motion force that exists between a moving ring-shaped component and an underlying surface. The effects of rolling resistance can impact the forward momentum of a ball, wheel, or tire. The principal cause of rolling resistance is the dissipation of energy between a rolling object and a road or surface. Under a moving vehicle, this energy loss could be due to either deformation of the tire or the road, or slippage between the tire and the road.
Deformation and slippage can both stem from numerous issues with the vehicle, its tires, the habits of the driver, and the conditions on a given driving terrain. Contributing factors typically include the condition of the tires, the alignment of the wheels, the temperature of the environment, the presence of rainwater, the speed of the vehicle, and the weight of the payload.
What Is Low Rolling Resistance?
Low rolling resistance is the goal of any truck or fleet operator who wishes to boost fuel savings and maximize vehicle efficiency. Commercial vehicle operators can achieve low rolling resistance in part with daily monitoring of tire inflation. Before each work shift, check each tire to ensure the air pressure matches the recommended level and inflate if necessary.
Another factor to consider is the type of tires in use on the vehicle in question. Do the tires have healthy tread and even alignment? Is the diameter sufficient for the payload? Some of today’s tires are specifically designed to decrease rolling effort and the consumption of energy on a given route. If the tires on a hauling truck are properly sized and inflated for low rolling resistance, drivers can maximize their mileage by inspecting tires daily and replacing them when necessary.
How Rolling Resistance Affects Fuel Economy
In 2012, Volvo and Michelin conducted a study on the correlation between emission reduction and the quality of a vehicle’s tires. The study found drivers can reduce truck emissions by up to 14.5 percent by considering factors such as tire type, air pressure, and wheel alignment. Financially, this translates to reduced fuel consumption and a possible savings of as much as $9,300 per vehicle.
When broken down into testing categories, the study also found proper wheel alignment reduces consumption by 2.5 percent, and correct air pressure reduces consumption by 1 percent. The researchers conducted this test over two weeks across 1,000 kilometers between adequately aligned and poorly-aligned vehicles.
As tests like this show, proper tire type, air pressure, and wheel alignment can help fleets save time and money. In doing so, fleets can avoid the problems that contribute to rolling resistance and lead to the following costly issues.
- Reduced productivity. One of the most significant consequences of rolling resistance is the impact it has on productivity. For example, the commercial trucking industry measures productivity in delivery volumes, which speed-reducing factors such as rolling resistance will inevitably slow. The problem can also lead to reduced productivity at construction sites and pressing plants.
- Excess fuel consumption. The issue of tire resistance will lead to higher levels of fuel consumption, which, in turn, impacts a fleet’s bottom line. Any level of resistance, no matter how subtle, will put a strain on a tractor trailer’s engine. That will cause the truck to exert more energy and burn excess fuel in the process. Over the course of a year, the increased fuel costs can be substantial.
- Gas emissions. As mentioned above, rolling resistance puts wear and tear on the mechanisms of a truck, thus straining the engine. As a vehicle exerts more energy just to function as before, gas emissions are liable to ooze from the exhaust system. Consequently, rolling resistance has ill effects on the environment.
- Frequent maintenance. When issues develop that bring about rolling resistance, such as imbalanced wheel-ends or irregular tire wear, a truck is liable to require repairs at more frequent intervals. Problems such as inconsistent tire quality and air pressure are contributing factors to rolling resistance, as are ambient temperatures, road conditions, and driver habits. When combined, the resulting rolling resistance will inevitably shorten the vehicle’s service life.
- Reduced safety. Anything that strains a set of tires will render the vehicle less safe for operation. The threat increases as rolling resistance places strain on the engine and cause issues that affect neighboring components. Whether you operate a utility vehicle, bus, or delivery truck, rolling resistance is a dangerous problem because of its straining effect on major vehicle components.
- Higher operating costs. As tire and engine problems increase due to rolling resistance, a fleet is bound to incur higher operating costs when more frequent maintenance stops get factored into the annual budget. That can gravely impact a fleet’s bottom line and lead to higher prices on the end customer’s.
- Downtime. As rolling resistance takes its toll on a vehicle and related issues mount, it forces a fleet to cope with increased occurrences of downtime. Depending on the severity of the problem and the number of vehicles affected, a fleet could suffer untold losses, especially in industries like construction and transportation, where just a few hours of downtime can have a significant effect on budgets and revenues.
- Slowed schedules. With or without occurrences of downtime, rolling resistance stalls vehicles’ ability to arrive at destination points on time. In the transportation industry, this can have serious consequences for thousands of paying customers. Among shipping fleets, rolling resistance can lead to stalled deliveries and reduced levels of productivity in a given workday.
- Reduced confidence. As issues with rolling resistance take their toll on a fleet’s ability to deliver as promised, the problem can negatively impact the fleet’s relationships with other businesses. If a fleet gets hit with a sudden spate of delivery issues due to rolling resistance, client businesses are liable to grow impatient and look elsewhere.
What Factors Affect Rolling Resistance in Heavy-Duty and Long-Haul Fleets?
Numerous factors can positively or negatively impact the rolling ability of tires on OTR or long-haul tractor trailers. Factors such as heat and pressure can help tires run smoothly if maintained at proper levels, but beyond certain thresholds, those same factors can be problematic. The following factors have all been proven to correlate with increasing rolling resistance.
- Road roughness. The roughness of a given road terrain can affect the level of rolling resistance a vehicle will encounter along a route. If the road is exceedingly rough, the tires will encounter rolling resistance of higher intensity. Other factors that might contribute to rolling resistance, such as heat and tire load, are liable to exacerbate the issue.
- Defects. If a set of tires are defective in any way, the issue will factor into the level of rolling resistance on a given terrain. The issue could be especially problematic if the defects on one tire are out of proportion with the other three, because this will render the vehicle unstable.
- Material density. Tread wear will affect a tire’s ability to perform along the roadway. If the tires are excessively worn, the tires will perform less efficiently down a roadway, and therefore encounter greater degrees of rolling resistance. Rolling resistance is yet another reason to replace worn tires.
While low rolling resistance tires may seem like the best option to combat this issue, according to Fleet Equipment Magazine, “The advent of low rolling resistance tires was a boon for fuel efficiency and SmartWay verification, but the tire construction, compounds and tread design that make those possible weren’t always the most durable, which could lead to reduced miles-to-removal.” New tire compositions and tread designs are being constructed to combat this downfall to low rolling resistance tires, but fleets can achieve low rolling resistance with their existing tires by installing IMI FLEXX in all wheels positions. Click here to learn how.
- Moisture content. The presence of water or moisture can affect the speed and rolling consistency of a set of tires. When roads are wet, the slickness will have a slightly destabilizing effect on certain tires, particularly those with poor traction. Over time, moisture can affect the tire’s tread and heighten the probability for increased rolling resistance.
- Road maintenance. The condition of a given roadway is one of the most common causes of rolling resistance. If a roadway has not gotten repaved for many years, the roughness of the terrain will cause higher degrees of rolling resistance. If a road is currently undergoing maintenance and the pavement is inconsistent, this too will affect a vehicle’s rolling efficiency.
- Tire penetration. The extent to which exposure has penetrated a set of tires will affect their ability to roll against resistance. Likewise, the extent to which rubber has penetrated the underlying pavement will affect the road’s ability to allow for the unimpeded flow of traffic.
- Tire diameter. The diameter of a set of tires is not so much an issue as long as the rubber is solid, the tread is in good shape and the air pressure is at the recommended level. As such, tire diameter is only a minor concern when it comes to rolling resistance. That said, problems can emerge if the diameter gets compromised by excess tire wear or insufficient air pressure.
- Tire pressure. The air pressure in a set of tires is an important factor related to increased rolling resistance. If the pressure is low, the vehicle is liable to undergo sidewall flexing and encounter increased rolling resistance. That can also lead to overheating, which would only intensify the issue. If the air pressure is too high, the vehicle could suffer a loss of traction and roll or skip amid increased rolling resistance. If the air pressure between a set of tires is inconsistent, the problem is liable to be even more intense.
- Tire condition. The condition of a set of tires is another concern when analyzing the causes of increased rolling resistance. Even though factors like density, road maintenance, driver speed, heat, and load are more consequential, a worn-out set of tires could make each of these factors worse. If your vehicle has become less efficient over time, a worn set of tires could be one of the contributing factors.
- Load Weight. The load on a set of tires can have a significant impact on a vehicle’s ability to roll smoothly and efficiently along a given roadway. If a vehicle is loaded to its full capacity, the level of rolling resistance will inevitably be more intense, especially on steep routes and along the gravelly terrain.
- Tire temperature. When it comes to rolling resistance, the issue of heat is a double-edged sword. In solid tires, increased levels of heat have been correlated to decreased rolling resistance, though the effect only works up to a certain temperature limit. However, heat can have ill effects on the condition of tires and ultimately lead to other problems that cause rolling resistance.
- Driver behavior. The habits of a given driver will invariably affect the degree of rolling resistance along a route. A driver with a wobbly grasp on the steering wheel and abrupt habits with the pedals is liable to encounter higher levels of rolling resistance than a driver with more even driving habits.
- Humidity. The temperature along a given roadway has a more direct correlation to rolling resistance, especially when compared to tire heat. That is due to the effects humidity can have on the surface of a driving terrain, as well as on the rubber of a set of tires.
- Precipitation. The presence of rain will affect the conditions of any given roadway, and rolling resistance is just one of the consequences. If it is drizzling, the wetness of the road will inevitably affect the rolling ability of a set of tires. A thick downpour affects tire traction and driving stability, and these issues play into rolling resistance.
- Ambient temperature. The temperature of the surrounding environment can have subtle effects on the driving conditions of a roadway, even without the presence of fog or rain. Uncharacteristically hot or cold weather conditions can affect a driver’s ability to operate a vehicle in comfort. Cold and humid temperatures also impact tire temperature, another issue that correlates to rolling resistance.
IMI FLEXX for Decreased Rolling Resistance and Increased Fuel Efficiency
On heavy-duty trucks, long-haul tractor trailers, buses, and other commercial vehicles, it is crucial to have tires that will experience low rolling resistance, even tire wear, and longer tire life. Fleets are consistently losing money from their bottom line due to excessive fuel consumption from increased rolling resistance – and IMI FLEXX can change that. Today, commercial fleets are using FLEXX to balance their wheel-end assemblies, reducing their rolling resistance and increasing fuel efficiency. Read how satisfied national fleets are here or contact our representatives today to learn more about FLEXX.