How Low Can You Go?

The search for ways to reduce weights and increase payload is leading truckers to make changes where the rubber meets the road. And it appears there may be less rubber meeting the road.

A trend toward smaller tires has several benefits and some drawbacks, but tire makers are finding ways to overcome the problems. Trucking companies are also getting improved performance from tires designed for specific applications.

The move to smaller wheels — on rims as short as 19.5 inches in diameter — is by no means universal, but some companies are trying to “lower the floor” on trailers to make it possible for them to carry more cargo.

A major drawback could be shorter tire life — because a smaller tire makes more revolutions per mile.

And, while truck manufacturers have reported that some customers are asking for 19.5-inch wheels, the configuration is extremely application-specific.

Charles Henry, vice president of industry relations at trailer maker Great Dane, said that the extra space gained by using smaller wheels comes with a trade-off.

“The point of smaller wheels is to lower the floor of the trailer,” he said, “but then it could be below many loading docks.”

Despite such reservations, Henry said Great Dane will build its trailers to use smaller tires at a customer’s request.

Tim Yglesias, director of product systems and components at Great Dane, said he noticed a “migration” to low-profile tires, which are smaller than in the past but fit on 22-inch rims.

Rod Ehrlich, vice president of engineering at Wabash National Corp., was enthusiastic about the use of small wheels and tires.

“We’ve got to get more useable space,” he said. “We are not permitted to go much taller — but there is no limit on down, except the highway.”

“Today, the 110-inch inside is the standard,” he said, but that standard will come to be 118 inches, or 9 feet, 10 inches.

As for the problem of loading dock height, Ehrlich said: “Air suspension is now a way of life in trailers. It is a huge trend — and the biggest fans are drivers.”

And adjustable air suspension, he said, eliminates problems with loading dock heights.

Plus, a lower center of gravity can improve the safety of tanker trucks.

Ehrlich said the smaller tires being made today are durable enough to make them cost-effective, but he doubts wheels will go smaller than 19.5 inches.

For the full story, see the April 5 print edition of Transport Topics. Subscribe today.