Out with duals, in with super singles

FARGO, N.D. – American truckers and farmers who haul bulk commodities are replacing their dual tires with super singles.

The move gains flotation in the field and fuel economy on the highway, but weight is the main factor.

Super singles are low profile, 17-inch wide tires that have a load rating equal to or greater than a pair of conventional 22.5 tires and a 50 or 55 aspect ratio.

They trim 200 pounds off each axle, freeing up an extra 400 lb. of legal load carrying capacity on the trailer. If they’re fitted to the tractor, the rig gains nearly 800 lb. of capacity over duals.

When comparing super singles on aluminum wheels to duals on steel, Michelin and Bridgestone say the overall weight savings can be as high as 1,300 lb., which is a weight reduction that can translate directly into payload.

Less rotating weight translates into better fuel economy, and sidewall flex is reduced because each trailer axle runs only four sidewalls instead of eight. Transport Canada says super singles can reduce fuel consumption by four to six percent.

The tires are especially popular with those who haul bulk commodities such as liquid, grain, gravel, sugar beets, distillers grain and feed.

These types of cargo can be precisely weighed as they are loaded, allowing drivers to put on every possible pound of product right up to the legal limit.

“Weight saving really is the biggest factor,” says Paul Gray of OK Tire in Fargo, N.D., which sells the Michelin X-One super single.

“The X-One has become very popular here in sugar beet country, but there’s more to it than just the weight. The trailer pulls a lot easier. I’d say nearly all the sugar beet trailers are on super singles, either our X-One or the Bridgestone Greatec.”

Having seen how they work on their neighbours’ beet haulers, Gray said grain farmers in the Red River Valley have recently started putting them on their hopper bottom trailers, which provides better flotation in the field and eliminates mud between the duals.

Although he hasn’t installed many super singles on drive wheels yet, Gray said the trend is starting to catch on.

“I have one customer at Minto, that’s up near the Manitoba border, and he’s had them on all his hopper trailers for a few years and now he’s installed them on all his drive axles as well. He says it’s working out pretty well for him.

“Again, it’s a weight thing. He’s gained almost 800 lb. of capacity on every truck. That’s a lot of extra payload if you’re running your trucks seven days a week.

“We’re starting to see some higher mileage X-One trailers now, guys that put on 300,000 miles or more per year. They’re telling me that the cost benefit thing is really in favour of the super single tires.”

Gray said the cost per mile is the same or less than conventional duals, but the extra 400 or 800 lb. per trip tips the scales in favour of super singles.

“For a regular farm grain semi, you don’t see those kind of high miles per year, so the dollar benefit might not be as great. But if you’re doing any custom hauling or long distance hauling with that rig, the wide tire is a good bet.”

Gray said super single tires are not designed for the front axle. The front steering tires that have been used for decades on heavy dump trucks and cement trucks are similar to super singles only in appearance.

Super singles are designed only for trailers and drive wheels and cannot take the side loads that a steering tire must absorb.

Some truck operators are reluctant to switch to X-One or Greatec because a flat will immediately bring the truck to a halt. There’s no such thing as limping to the next town on the remaining dual tire.

Gray said he’s heard of the concerns but it hasn’t proven to be a problem.

“One of our biggest customers is Trans-Systems. They haul sugar beets here in the valley. Since they’ve gone 100 percent to X-One tires, their down time hasn’t been any different from when they ran conventional duals.

“Now, that’s all interstate trucking, from the beet dumping depots to the sugar beet plants. There’s no rough terrain.”

Gray said he would probably stay with duals for better reliability if he were hauling in and out of scrap yards or corn stubble fields.

New tires versus retreads also affect reliability, he added.

“If you’re running virgin tires, you’re always less likely to have flats. That applies to super singles or conventional duals. When you run retreads of any kind, you increase your downtime.”

Grey said retreading super singles is a problem.

OK Tire runs its own Bandag retreading plant with a modern, robotic Bandag machine, giving it years of experience recapping truck tires.

“Normally, the machine does a better job, but we’ve had some issues with these tires. There’s problems getting the layers straight. It’s a lot more difficult than retreading a regular tire. I’ve got a couple customers who just recently put X-One retreads on their drives. So we’re waiting to see how that works out.”

Gray said flats and blowouts are less of a problem now, whether using new tires or retreads, because more operators are paying closer attention to tire pressure.

“We’ve always known that the best way to cut downtime is to pay more attention to tire pressure. Valve cap monitors and air lines do a better job of that than the old hammer.”

Gray said there’s not much difference in cost.

If opting for conventional duals, two new aluminum wheels cost $250 each, for a total of $500. Two new premium quality 8.25 x 22.5 tires cost $400 to $450 each, for a total of $800 to $900. This means one corner of the trailer costs $1,300 to $1,400. Four corners cost $5,200 to $5,600.

If opting for super singles, Grey said one wide aluminum wheel costs slightly less than $500. A Michelin X-One tire costs $850. Total cost for one corner of the trailer is $1,350. Fours corners cost about $5,400.

“The problem comes if you want to retrofit your existing trailer. You’ve got to find a home for those duals. If you can get a decent price for the used stuff, it’s not such a big investment.

“Or, if you’re buying a new trailer, you simply order it with the tires you want. Then it’s basically a wash, cost wise.”

For more information, contact Paul Gray at 701-277-8426 or visit www.michelin.ca or www.bridgestone-trucktires.com.

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