"As we continue the national and global discussion of conserving energy, fossil fuels and other natural resources, this technology is a solution that is making a difference today." [xfloat=right]http://www.cleanmpg.com/photos/data/501/Trailer_with_Single_Wides_installed.jpg[/xfloat]Wayne Gerdes – CleanMPG – Mar. 25, 2009 Oak Ridge National Lab's four-year study compares Michelin(R) X One(R) tires to duals. Weight savings of up to 1,200 pounds per rig can be exploited for additional load with a smaller increase in FE. One less load for every 50 trips is a 2% savings just on the weight reduction alone. Greenville, SC. -- A 383-page report made available last week by the Department of Energy's Oak Ridge National Laboratory confirms that Single Wide truck tires are much more fuel efficient than duals on heavy trucks. More than 700,000 real-world miles were driven by six instrumented tractors and 10 trailers over the course of the four-year test. "If fleets and owner-operators needed more proof that wide singles can save fuel costs, look no further," said David Stafford, chief operating officer of Michelin Americas Research Company (MARC). "This real-world field testing confirms what our engineers and designers have said since we launched the Michelin(R) X One(R) nine years ago - that replacing duals with wide single tires not only reduces rolling resistance and saves energy, but also reduces the amount of CO2 we put into the atmosphere." Data collected during the tests includes instantaneous fuel consumption, speed, acceleration, gear, location, time of day and grade. Half of the tractors were outfitted with Michelin X One single wide tires while the other half where equipped with standard dual tires. Half of the trailers were outfitted with Michelin X One single wide’s, two with standard dual tires, and three with dual retread tires. Oak Ridge researchers found significant fuel efficiency improvement over dual tires when wide singles were in use - 6 percent overall and 10 percent with fully-loaded tractor-trailers. "Our tests have found wide single tire technology to be more fuel efficient in a variety of real-world conditions," said Bill Knee, director of vehicle safety research at Oak Ridge National Laboratory.
I always wondered why use two tires instead of one wide one. I was guessing the structural integrity of one tire with two sidewalls isn't as good as one two tires with 4 sidewalls, so these tires are probably more expensive and also made differently. LRR wouldn't be bad to add to the list either
I'm wondering about the safety aspect of replacing duels with singles. If one of the tires in the dual set blows, the remaining tire is still there to carry the weight until the trucker can pull off the road to replace the flat tire. If the single tire blows, especially on single rear axle tractors and trailers, then that side of the truck or trailer is rolling on rims with much less controllability. It would be less of problem on dual rear axle tractors and trailers.
My thought exactly. I don't claim to be a tractor trailor safety expert, but this question needs to be answered.
That's a good question. There are a couple answers I guess. First is that we deal with that with the single steer tire already. A failure of one those becomes catastrophic only when it occurs on a high speed curve, the driver panics, or the tire pieces takes out something mechanical to help control the truck (I've never heard of, but possible). There are times when a tire on a dual set blows a hole out its sidewall and takes out the tire next to it (usually when the inside dual goes first), so the effect is the same as having a super single fail. Most failures are caused by run-flats: the tire pressure is too low and the tire overheats causing a sidewall blow or tread separation. The problem with dual tires is that the properly pressured tire supports the low tire, hiding the problem. It is much easier to catch problems with a single tire. Drivers who regularly check their tires just don't have tire failures that often. I thump my tires with a 2# hammer nearly every time I stop on the road, and have enough practice to tell tires dropped to 70psi from 95psi. I've caught a couple tires like this. I also feel the tires for heat. If one feels significantly hotter, I know I got a problem. I wish I could say that I've never had a tire "blow" on the road, but it happened only once. I may have picked up large bolt, there may have been a weakness in the tire because of an impact (curb, other object), or frankly, I might have missed the low tire. My point, besides bragging, is that good drivers minimize tire failures because they pay attention, and super singles make it a little easier for even marginal drivers to see problems before they occur. Finally, IMO, not many operators will put super singles on their single axle tractors. Typically these are not weight sensitive operations (or they would be tandems), thus negating that advantage, plus less sidewall flex with lower weight negates some of the FE advantage. Keith
It isn't that unusual to see a rig limping along with one blown tire on a dual set (is it legal though?). Presumably limping to a service facility is cheaper than waiting for a mobile unit to come fix a tire on the roadside. Maybe repair cost and downtime to repair also factor into the operator's decision.
Does the suv driver on the right realise his precarious position?? I've seen the odd truck listing like that after it blew a super single tire. It is a real problem around here and i am constantly dodging bits of tire rubber or seeing it on the roadside. Having said that, some of it is from dual tires. ollie
One evening some years ago I saw an 18-wheeler on I-95 with a blown tire on the trailer (dual tires, way before super singles existed). The tire was completely gone from the rim but the other tire in that pair had at least some air in it. The rim of the blown tire was glowing molten orange from contacting the pavement, and fragments of molten steel were flying off the rim as it disintegrated. Spectacular!! @kngkeith: would the other tire have to have been low on air for the adjacent rim to contact the pavement?
Yes. But, I'm guessing, that what you saw in the evening was sparks as the steel belts from the disintegrated tire brushed against the pavement. Rims typically don't get red hot unless the hub cooks. Then the tire gets hot enough to blow, or start on fire. Anything is possible, and I imagine it was quite a show. The driver was foolish to not stop if the rim was that hot, because other damage was occurring to the hub and axle, and the danger of a tire or trailer fire was very real. Keith
