The Rolling Resistance Paradox
Photo: Jim Park
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Photo: Jim Park
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Be careful what you ask for because you just might get it. If the lowest possible rolling resistance is your only consideration when spec’ing tires, chances are you’ll be mighty disappointed in the tire you get. In fact, no tire maker in the world would even offer such a tire, but it’s theoretically possible.
If you want really low rolling resistance, try steel wheels, as in train wheels. Steel-on-steel has almost no rolling resistance, but almost no traction either. They’ll last a good long time, but drivers wouldn’t be happy with the ride. I’m using an absurd example to illustrate the point, but an extremely low rolling resistance tire would have similar properties: traction and ride would be poor, the tires might last 50,000 miles, and it would cost you much more over a two-year time frame than the value of the fuel they saved.
Tire makers often express the design goals in the form of a triangle, each axis being one of three important considerations: traction, tread life, and rolling resistance. Historically an improvement in one forced compromises in the other two, but that’s not universally true anymore. Through tire design, it is possible to use technologically advanced compounds and tire-construction techniques to minimize a tire’s rolling resistance with little or no impact on traction or tread life.
“A number of factors influence a tire’s rolling resistance, including the compounds used, casing design and tread pattern,” says Bill Walmsley, product category manager, Michelin Americas Truck Tires. “In most cases, the depth of a tire’s tread blocks is inverse to rolling resistance. The deeper the tread blocks, the better the grip but the worse for fuel economy.”
Sidewall construction can also reduce rolling resistance. However, there are some tire design options available that can lower the rolling resistance, such …Read the rest of this story
