Technically, Super Singles are single tires that offer the capacity to replace the capacity of a dually set. Most commonly the term refers to wide-base tires (their proper name) used to replace dual-wheels on semi-trucks and trailers. This approach turns 18-wheelers into 10-wheelers. In the semi-truck world, super singles can reduce the rolling resistance and weight of a truck and trailer and have been shown to improve fuel economy by up to 3% percent.
DUAL TIRES VS. SUPER SINGLE TIRES: WHICH IS BETTER?
Depending on your trucking application, one may be better than the other. Discover the advantages and disadvantages of dual tires and super single tires and make the right choice for your fleet. Dual tires have been used on multiple fleets for decades to keep trucks stable and ensure safety in the event of tire failure.
Dual Tires Advantages:
- Dual tires are typically used for non-steering axles and are best for heavy-duty commercial fleets.
- You’ll maintain drivability in the event of a flat as the other three wheels on an axle will compensate for the blown tire.
- Fuel economy is only 3% less compared to super single tires.
Dual Tires Disadvantages:
- Space between the dual tires must be maintained to prevent rubbing and lodged debris.
- An underinflated or flat dual will cause uneven wear on the other tires.
- Inner dual tires are often difficult to reach to monitor air pressure.
SUPER SINGLE TIRES
Super single tires often eliminate the disadvantages created by dual tires on a commercial fleet. They have been increasing in popularity which has led to improved design and functionality.
Super Single Tires Advantages:
- Super single tires have a more substantial contact patch than standard dual tires, which increases a fleet’s load capacity.
- They also eliminate hard-to-reach tire pressure monitoring, especially on the inside tire
- Super single tires can improve vehicle performance, create a smoother ride and reduce fuel consumption and maintenance costs.
- Highway routes, bulk commodities, and long-distance fleets are perfect applications for super single tires.
- Overall tire weight is reduced which could allow for extra freight.
Super Single Tires Disadvantages:
- Super single tires don’t have the built-in backup in the event of a flat tire.
- In the case of a flat tire, one could drive to a tire facility with conventional dual tires but not so with Super Singles which will require roadside assistance or a tow.
- Super single tires can be harder to find out on the road when a replacement is needed.
Super Singles offer improved smoother rides along with increased fuel mileage but are still unlikely to replace conventional dual tire setups.
The history of super single tires for Heavy Trucks and the highways had its ups and downs. They gained popularity when first introduced because they cut fuel consumption by as much as three percent.
But with everything new, the new technology had some problems. The main one was that the semi-truck went down when a tire blew.
An Over the road Truck Driver, recently made the following statement with a trucking magazine, “I went for a ride in a truck with a super single setup, the same model as mine, and was quite impressed with the soft ride. I especially liked the fact that with the wider tires, the truck didn’t fall into road ruts.”
Another driver that had an opportunity to drive with Super Singles had said, he tried super singles when the company bought some used equipment that already came with Super Singles. He said they tended to plow in heavy snow instead of cutting through it like conventional tires.
Super Singles and Snow Chains
Chaining up was really problematic because they have such a wide base across, so the chains didn’t fit as well and they shifted around too much, which was another issue mentioned.
The law says you have to chain up two tires on each side. That isn’t too hard with conventional duals because you just chained the outer two tires. But with super singles, you’re still required to chain up two tires per side, but now you have to struggle with that wide surface putting on your snow chains. That’s the chains that would normally go over both drivers. It can become very time-consuming and hard work in the cold weather. Usually, it’s a blizzard, cold, and cars and trucks zipping by.
Super Singles have been questioned on ice road conditions as there aren’t enough edges and some say they really shouldn’t be used in the mountains. However, they are common on straight Interstate highways in the southwestern and southeastern United States.
Super Singles are Best for the Interstate Highways
Kal Tire representative Colin Rafferty said super singles were designed for Interstate highways. They originally enjoyed a four percent fuel savings over conventional tires due to less rolling resistance. Because of improvements in conventional dual tires, that margin has narrowed to about one percent, still leaving a 3% fuel savings.
There a weight benefits, comparing Super Singles vs Conventional Dual Tires. Super singles shave off approximately 200 pounds per axle. “You have one rim instead of two, two sidewalls instead of four,” said Rafferty. “If you’re a bulk carrier hauling concentrated amounts of weight, super singles give you an advantage. That’s where that 200-pound saving per axle starts to pay off.”
Super Singles in Canada
In Canada, when super singles came out, they were only allowed to carry the maximum weight allowed in the States, and that was actually a reduction in your payload.
Availability is the other factor in Canada. It’s a non-standard product, so most tire dealers don’t always keep stocked inventory. There’s no advantage in terms of cost. Buying 2 conventional tires will cost you about the same as buying one super single.
Nor is there a capacity advantage. Rafferty said two standard duals are actually rated to carry more than a super single, but the point is moot since carrying capacity is not determined by the tires but by provincial and governmental regulations. Whether fitted conventionally or with super singles, the same maximum weight per axle regulations apply — and this is less than either setup is actually capable of carrying.
Rafferty said Kal Tire concentrates their super single inventory at dealers along the TransCanada coast to coast. They don’t carry much inventory off that main thoroughfare.
Drivers found that if they had a flat on the trailer, they had to call a tow service that would have come and chain up that side of the axle and limp to the next town. Usually, you were out of luck finding a replacement
Can a Super Single Be Retreaded?
Retreading super singles is another issue, not many retreading facilities have made the required investment and additional equipment. Re-treading plants reject about half the super single casings they get. The reason is that highways are rutted. The wide single tread is about 18 inches wide, so the tire doesn’t sit flat. It creates waves across that wide surface and causes issues in the retreading process.
Alternative uses for Super Single Tires
Overland vehicles have long used super singles as it has meant improving off-road performance and giving their vehicles a heavy dose of the go-anywhere aesthetic.
Most famously, Earthroamer converts their trucks from the factory 32-inch diameter, 6-inch wide, 10-ply dual rear wheel tires to single 41-inch diameter, 12-inch wide, 22-ply military tires. This gives their motorhomes better tracking on off-road trails and eliminates the potential of rocks getting stuck between the duallies.