LRR Tyres for green future
Tyre industry plays a significant role in environment protection, thanks to increasing number of regulations as well as rising competition from within the industry. Minimising impact on environment is no more an option. One of the ways the industry is doing its part is by helping to improve vehicle fuel economy and decrease emissions through lower rolling resistance of tyres
There is no doubt that consumers are willing to pay premium for tyres with more features, such as longer warranty. I am also sure that tyre manufacturers perform life cycle analyses for their product offerings, taking into account production + sales + service costs, customers’ ownership costs and tyre end-of-life considerations – such as environmental impact. Globally, billions of scrap tyres are generated every year. Fortunately, more than 90% of scrap tyres are used up, both in recycling and other beneficial uses, and less than 10% are estimated to end up in landfills.
Tyre industry is doing its part, due to competitive as well as regulatory reasons, to minimise environmental impact. One of the ways the industry is doing its part is by helping to improve vehicle fuel economy and decrease emissions through lower rolling resistance of tyres.
From Newton’s second law of motion, when a vehicle is coasting on a uniform road gradient and surface, factors affecting motion are rolling resistance, air resistance, and the pavement gradient angle. Hence it is not too difficult to calculate the rolling resistance of a given set of tyres, under controlled conditions. The coefficient of rolling resistance (CLR) ranges from 0.01, on a particularly smooth and even test track to 0.021.
It has been reported that going from the highest CLR to the lowest, fuel consumption could be lowered by up to 9%, all other factors remaining the same. But in reality, the actual fuel economy realised by drivers depends upon a myriad of other factors, such as tyre tread condition, inflation pressure, speed, type of road, driver skill & habit, engine condition, just to mention a few.
When you put new tyres on in place of old ones, your fuel mileage will always drop, regardless of how low the rolling resistance on the new tyres actually is. The only fair comparison is between brand-new tyres and other brand-new tyres, or between tyres worn to the same degree.
Second, when using low rolling resistance tyres, there are two related factors that are easily as important to real-world fuel-efficiency as the tyres themselves.
Motor oil: Using the correct weight (viscosity) of oil in your car will cut down on engine friction, and this accounts for at least as much in fuel-efficiency gains as the tyres.
Tyre pressure: Even slightly under-inflated tyres will quickly bleed away any fuel savings that one might gain from LRR tyres. To get the best fuel savings from your LRR tyres, it’s best to check the pressure literally every time you fill the tank.
Will low rolling resistance (LRR) tyres save enough gas to justify their cost?
The US Department of Energy says five to 15% of fuel economy is used for overcoming rolling resistance.
Of course, it’s not as simple as just switching tyres and saving money. The extra cost of LRRs (some run as high as $170 each) means that you’ll probably come about even in spending. However, a car marketing firm says that almost none of the tyres would save money for the people who bought them. In the best case, you’d save about $52.50 per year if you drove 15,000 miles a year. Outside of USA, very few cars are driven to this extent, and their savings would be even lower.
But carmakers will inevitably be drawn to these tyres as they try to meet the new 35.5 mpg USA Corporate Average Fuel Economy (CAFE) standard for 2016. Incidentally, you could do a lot to help your fuel economy if you just properly inflate your tyres.
A major tyre manufacturer’s study found that 93.5% of European cars have under-inflated tyres, wasting 2.14 billion gallons of fuel a year. Similar situation is observed in most countries.
In any case, using LRR tyres would help the greenhouse gas and local polluting emissions, and that’s the main reason people need to consider EV’s and hybrids in the first place. Save a gallon of gasoline, and you also prevent up to 20 pounds of carbon dioxide from entering the atmosphere, making fuel economy savings secondary