As a result of rising CAFE standards and the consumer demand caused by rising fuel prices over the last decade, more car manufacturers are paying attention to fuel economy, as significant selling point. In coordination with tire manufacturers, they have developed tires with lower rolling resistance, as the direct answer to the present situation in the market. Although they made their grand entry on hybrid cars, where they stood as yet another in the long line of energy-saving technologies, LRR tires are facing an increased demand among the mainstream drivers.
What is Rolling Resistance?
Rolling resistance is the force which is required to maintain your tires rolling at given speed. As tires change shape as there rotate, the part of the tire in contact with the road is deformed before it returns to the original state. Underinflated tires, for example have high rolling resistance. Overinflating them would minimize their rolling resistance but at the expense of ride quality and safety, as it becomes bumpier as the tire pressure grows. And higher the pressure, smaller the contact surface, which implies less traction and reduced controllability.
How Does It Work?
Manufacturers claim that lower rolling resistance technology maximizes the fuel economy using different methods. So, while experts agree that it is internal friction that offers significant room for improvement, the tread compound can also be redesigned in order to reduce rolling resistance. However, reducing the contact surfaces between the tires and the road readily involves trade-offs in grip during braking and cornering. The big question is whether you prefer performance and safety or fuel economy.
What Does Affect It?
Besides reducing the contact surfaces between tires and the road, manufacturers have developed a number of other techniques. One of important variables is a tire composition. By adding silica to the standard compound of natural and synthetic rubbers, rolling resistance can be decreased without sacrificing traction and the good grip in the critical stages of driving. There are practically endless choices of tires, for example tires with reduced depth of tread blocks are going to be more economical, as deeper treads involve more flexing as they roll.
The Numbers
It’s little known that most of the fuel energy is actually spent to overcome inertia when accelerating and decelerating and aerodynamic drag. The tires’ rolling resistance makes up to 4% of the fuel consumption in town and about 7% on the highway. It was established that a 10% decrease in rolling resistance results in 1-2% in fuel economy. It doesn’t seem much, but it can add up if you calculate how much you drive a year.
Your Mileage May Vary
It’s really hard to tell if LRR tires cost more than others. It depends on the tread compounds and the tire structure, and more importantly whether you are pointing at the initial price tag or the overall cost of ownership. While it’s true that their fuel saving properties are increased, low rolling resistance tires have less tread life, which than can neutralize the energy savings.
Eventually, is there any way to decrease your car’s rolling resistance without investing in low rolling resistance tires. Some experienced drivers will tell you that the most important thing about all tires is to make sure they are properly inflated according to the car manufacturer’s recommendation.
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