You have certainly heard about this term while searching for new tires. You probably also know that the lower this resistance is, the better for your car. But what exactly does tire rolling resistance mean? And how does it impact vehicle traction, grip, and fuel consumption? That's exactly what we will be talking about in this section.
In fact, the rolling resistance is nothing but the amount of energy the tire consumes when it's rolling on the road. Higher or lower energy consumption depends on how much the tire deforms while rolling and the power the engine exerts while propelling it forward.
Actually, several factors influence the tire resistance rate, apart from their degree of deformation. The list includes tire pressure and how optimal its level is, the materials that the manufacturers use, the diameter and size of the wheel, as well as its tread pattern. The idea is that the more energy is used to propel it forward, the higher the tire rolling resistance. As a result, one of the most significant side effects is high fuel consumption.
Analysts found that fuel consumption increases on average by 3-5% in the context of a 30% increase in tire rolling resistance. What other aspects influence it and can we do anything to reduce it? We find it out right away from the post that follows.
Factors Influencing Tire Rolling Resistance
As mentioned before, several factors influence tire rolling resistance. these include natural factors like size, width, and tire construction, as well as "anthropic", as I call them, i,e. tire pressure. I call them like that because depending on the tire pressure, the rolling resistance can be higher or lower. So, the driver can influence it directly. Let's take them one by one to get a better picture:
- Tire Pressure
How do you think the pressure in your tires influences their rolling resistance? It depends on the pressure level, actually. If we talk about overpressure, the tire is less prone to deformation. And reduced deformation is equivalent to reduced rolling resistance, which would result in lower rolling resistance. This is the reason why many drivers choose to add some extra PSI to their tires in the false hope of improving fuel efficiency.
BUT: while higher pressure might be beneficial in some circumstances, keep in mind that overinflation leads to other potential risks such as a blowout. So, the benefits do not really justify the risks and it would be good to maintain optimal tire pressure.
On the other extreme, underinflated tires are expected to generate higher rolling resistance. this is because there is more rubber on the road to propel. As such, the engine exerts more effort, which, consequently, burns more fuel.
Therefore, the best we can do as drivers is to maintain the recommended pressure in our tires. This is the easiest way for our tires to roll the way they should, without causing unwanted side effects.
- Tire Size And Width
Tires with smaller diameters tend to generate higher rolling resistance. In the same context, the resistance becomes much lower as the width of a tire is larger.
- Tire Construction
A no less important aspect is the tire construction. If a tire has less material in its architecture, then less material is prone to deformation. Take for example a sedan summer tire vs an SUV winter tire. The elasticity of the tire material also matters enormously. Energy is consumed much less when the material is more flexible.
Also in this context, tire tread patterns are directly proportional to how much energy the tires consume while rolling. Aggressive, bold, and tall treads are detrimental to rolling resistance. Subsequently, those that have smoother and shallower treads will be much more beneficial from the rolling resistance perspective. Either way, the manufacturers do everything possible to find the golden mean from all standpoints.
The Role Of Tire Grip Over Rolling Resistance
Would be easy to think that the ideal tires should be those offering the lowest rolling resistance possible. That would bring great fuel economy to every driver. But, things don't work just like that. The lower rolling resistance is likely to impact tire grip on the road. So, tire makers find it difficult to reduce rolling resistance to the maximum without affecting grip. Therefore, they find the perfect balance between optimal rolling resistance AND grip, which are both crucial aspects of vehicle performance.
The bottom line is that a certain resistance while the tire is rolling is necessary. And yet, is it somehow possible to benefit from both a great grip and a low rolling resistance rating?
LLR Tires
Answering the previous question: yes, it is possible to benefit from both a great grip and a low rolling resistance. This is because manufacturers constantly improve tire advanced technologies and visions. As a result of many tests and trials, they created LLR tires. These mean Low Rolling Resistance tires. Their purpose is to combine the benefits of a low resistance rating, high grip, and optimal fuel consumption.
The manufacturers have a different approach to the production of these tires. First of all, the architecture of LLR tires differs from the traditional one. The goal is that the tire keeps its integrity as much as possible by reducing deformity ratings while rolling. As long as it keeps its shape, less energy is consumed, which leads to more friendly fuel consumption.
Secondly, manufacturers draw attention to the weight of the tire. According to physical laws, the heat generated by a massive object is much greater than that of a small object. Starting from this premise, manufacturers seek to reduce tire weight. And they achieve it through special materials, which is the third specific feature of LLR tires. Manufacturers find alternatives for traditional rubber, mixing it with components that dramatically reduce its weight, keeping its flex and resistance at the same time.
Best LLR Tires
Tire Rolling Resistance: FAQs
What is Meant By Tire Rolling Resistance?
All tires are subject to different forces that act on them to propel them forward. The totality of these forces determines the effort exerted by the engine to keep the vehicle in motion. This effort, or energy, is also called rolling resistance and includes factors such as the weight of the vehicle, friction against the road, and gravity, among others. The greater the effort or rolling resistance, the more the vehicle consumes fuel or electricity if we are talking about EVs. In the modern industry, tire manufacturers aim to reduce tire rolling resistance as much as possible for the economy of drivers and the reduction of CO2 emissions.
Is Rolling Resistance Better High or Low?
The lower the rolling resistance, the better. Statistics confirm that low-rolling-resistance tires help save about 10% of fuel. Globally, this drop has a significant impact on the reduction of gas emissions. In addition, drivers also benefit from advantages because they pump fuel a little less often, which reduces their expenses.
What Increases Rolling Resistance?
Several factors can influence the rolling resistance of tires. These include but are not limited to the architecture of the tire, especially the tread, the size and width of the tire, as well as the pressure in it. If the tire is not properly inflated, the rolling resistance will increase which will lead to more fuel consumption.
Is Rolling Resistance the Same as Friction?
These two terms are usually used interchangeably. In fact, the rolling resistance is a form of friction. The rolling resistance is a force that opposes the rolling of an object, in our case - tires. The definition of friction is the resistance encountered when one body is moved in contact with another. So, basically, the two terms are somewhat synonymous.
Why Do Narrower Tires Generate Increased Rolling Resistance?
The answer lies in the degree of tire deflation. It may not be something clearly visible to the naked eye, but any tire is subject to deflation under the load of the car body. This leads to the formation of more contact with the road. The narrower tire patch has a thinner and more elliptical contact patch.
On the other hand, the wider tire has a more flattened area. This shorter patch doesn't affect the rolling resistance that much. Conversely, the elongated area of the narrow tire is likely to generate more deformation during rotation as it loses more of its roundness. As a result of greater deformation, the narrow tire generates higher rolling resistance.
Does Rain Increase Rolling Resistance?
Actually, yes. Rolling resistance means the force with which the rolling of the tire opposes any liquid or solid surface. In the given case, the water will make the rolling of the tire slightly more difficult because it exerts additional effort to drain the water from its path. Tire manufacturers constantly optimize tire designs to evacuate water as easily and efficiently as possible.
While the results are spectacular, the rain will anyway contribute to increasing rolling resistance compared to rolling on dry land. However, it's worth mentioning that a lot depends on the type and design of the tire. If we are talking about tires with a tread oriented towards wet roads, the rolling resistance will not be much higher.
What Other Factors Affect Rolling Resistance?
- 1. Ground conditions
- 2. Load conditions.
Rolling on loose terrain will add some effort for the tires to move forward. The additional load will also increase the rolling resistance because the deeper the tire sinks into the terrain/road, the higher the effort to keep moving.
Improper tire pressure will inevitably influence the rolling resistance. Underinflated tires lose their shape and more effort is needed to propel more rubber on the road. It's essential to keep tire pressure at the recommended levels.
Does Weight Affect Rolling Resistance?
Yes, it does. The more weight you put on your vehicle, the more effort it will take to roll on the road. Specialists recommend avoiding overloading the vehicle with unnecessary stuff that adds extra pounds. Also, drivers must take into account the load capacity of their tires.
What is the Rolling Resistance at Zero Speed?
Zero speed means zero rolling resistance. The rolling resistance force is applied while in motion exclusively. Tires do not generate any force when they are in a static condition. The force starts to manifest in a dynamic state when the speed, road surface, air resistance, and vehicle load influence the way the tire rolls on the road.
How Do I Know if My Tire is Low Rolling Resistance?
A regular tire is slightly different from an LRR (low rolling resistance tire). The latter has shallower tread blocks and thinner sidewalls. In addition, manufacturers use special rubber formulas in LRR tires. All these features work together to reduce the tire rolling effort on the road, which optimizes fuel consumption.
Which Tires Are Recommended For Low Rolling Resistance?
Here you have some great models for when low rolling resistance is a priority for you. The following models are among the top options according to Consumer Reports' independent ratings and customer reviews.
Bridgestone Ecopia EP422 Plus
Michelin Energy Saver A/S
Hankook Kinergy 4S2 H750
Continental PureContact LS
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