Wide-base, schmide-base. Who really cares about wide base tires? Well not many trucking fleets used to care, since wide base tires' taller profile, harsher ride and problems that occur when a tire goes flat overrode their desire for fuel savings.
But with the developments that have been taking place in the tire industry, there is renewed interest in a new generation of super single tires.
Their promise of improved fuel economy is making many over-the-road fleets salivate at the potential savings they offer-especially in these times of erratic fuel pricing and shrinking profit margins. Most fleets are at least curious about them and wonder whether they should be looking at them seriously. Perhaps you've been getting some questions from your fleet accounts.
Old vs. new
The old series 65 wide base tires like the 385/65R22.5 and 425/65R22.5 have been used for many years by many tanker fleets, bulk haulers and cement mixers that are extremely weight sensitive or need extra load-carrying capacity. A vehicle equipped with these wide base tire and aluminum wheel assemblies can save between 1,032 and 1,230 pounds of weight when compared to a vehicle with dual tire and steel wheel assemblies.
Vehicles are spec'ed from the factory with these tires since wider axles are required and gearing is different than for the smaller dual tires. Retrofitting can be done but is expensive and complicated.
Fleets using these tires predominantly operate locally or regionally rather than long distance. That's because regulations that limit the amount of load a tire can carry per inch of width varies from state to state and prevents the use of these tires by fleets that operate nationally.
The new wide base tires are produced in 445/50R22.5, 435/50R22.5, 435/45R22.5 and 495/45R22.5 sizes and offer several advantages over their predecessors:
1. Retro-fit: Since these new wide base tires have the same overall diameter as low profile 22.5 tires, a fleet can simply replace the duals with new wide base tires without having to make any modifications to the existing vehicle like installing wider axles or changing the gearing. Also in an emergency, if a wide base tire fails and a replacement is not available, it is possible to put two dual tires back on and continue down the road.
2. Inflation pressure: The same inflation pressure is used in the new wide base tires as in standard 22.5 low profile tires. These new tires require 100 psi instead of the 125/135 psi that the old 65 series tires require. This makes tire pressure maintenance easier, is better for pavement life and softens the ride for the driver.
3. Improved ride: In contrast to the earlier wide base tires, these new generation tires provide an improved ride over even a dual pair of tires, as well as improved traction on winter roads.
4. Inch width laws: Inch width laws are intended to avoid rutting of highways and while the rules differ across the country, the toughest is 500 pounds of load per inch of tire width. That means that a tread on a wide base tire must be 17 inches wide in order to carry 8,500 pounds or 17,000 pounds per axle and 34,000 pounds on a tandem. The new wide base tires comply with this strict regulation so these tires can now travel across the country without encountering a problem at any state's scales.
5. New tire design: The new wide base tires have a flat crown radius that makes them less sensitive to load variations. This is important especially when trailers are running empty. The additional rubber on the road reduces hop that causes irregular wear. Their belt design reduces the stress between the working plies that contributes to high heat generation. And as we all know, reducing heat in a tire improves casing durability.
6. Fuel efficiency: All wide base tires are more fuel-efficient than traditional dual tires. With two sidewalls instead of four, there's less energy generated in flexing. Since they reduce the weight of the vehicle as well these tires have much less rolling resistance so fuel savings results.
However, the new wide base tires are compounded to be fuel efficient as well, whereas the old wide base tires are designed for dump truck and cement mixer operations and are not fuel efficient.
The result is the vehicle equipped with these new wide base tires consumes a minimum 4 percent less fuel than those equipped with traditional duals. (Some fleets have reported 10 percent fuel savings.)
7. Tire mileage: Tire compounds have been designed for long wear. Combined with these tires' new construction, no sacrifice should be seen in removal mileage when compared to traditional dual tires. With 65 series wide base tires, drive tire wear was poor.
8. Retreadability: You retreaders will be glad to know that the new wide base tires are definitely suited for retreading and structurally have nothing that would prevent their being given a second or third life. Their casing life should be similar to traditional dual tires. Any retread system can be used to retread them, although your plant equipment will probably have to be modified to handle these behemoths. It is recommended that fuel-efficient compounds be used on these tires to return them to a thoroughly ``like new'' condition.
Pluses, minuses
Wide base tires in general provide a number of other advantages such as:
* Ease of inflation maintenance, since there are no inside duals to inflate and only one valve on an axle end;
* Improved vehicle stability as a result of a wider axle track and lower center of gravity for tankers;
* Reduced costs, since one wide base tire costs less than two traditional dual tires and less federal excise tax is assessed; and
* Reduced irregular wear, since mismatching of dual tires by size and inflation pressures is no longer an issue.
Now of course there are some disadvantages fleets should be aware of. The first is availability.
Michelin is marketing its X-One line of wide base tires, Bridgestone/Firestone offers its line of Greatec drive and trailer tires, and Goodyear has introduced its Marathon trailer single. (Continental also is due to enter the market with testing some time this year and with product in 2003 or 2004.)
Since this is new technology, not all sizes may be available right away in every location in which they are needed. But this problem will eventually fade away as with all new products.
New wheels are required, of course. Wheels specifically designed for these tires are available from Accuride and Alcoa that have a 2-inch outset. These wheels move the tires out and provide the added advantage of improved braking and extended brake drum and lining life since the running assembly is better ventilated and stays cooler.
Fleets still have the problem associated with flat tires. When one wide base tire goes flat, the vehicle is down. There's no ``limping it in.'' The size and weight of the tire and wheel assembly is going to make emergency road calls really challenging for servicing technicians as well as make normal tire changes much more backbreaking.
A wide base tire mounted on an aluminum wheel weighs about 260 pounds and mounted on a steel wheel weighs about 320 pounds! Don't be surprised if workers' compensation claims increase due to this. I'm sure new tools will be designed in the near future to address this task should these tires gain in popularity.
So what types of fleets would want to use these new-generation tires?
Long-haul and regional fleets that are interested in reducing their fuel costs; any weight sensitive operation such as tankers and bulk haulers, and even reefer fleets that carry a lot of extra weight in refrigeration units and trailer insulation; and fleets that operate their vehicles on-off highway and require higher flotation tires would be interested in these tires. They can be used on drive axles, trailers and dollies-anywhere dual tires are now used.
Training's a must
There is, however, one caution here: You can't allow your fleet customer to try these tires by slapping a set on a vehicle and telling the driver to jump in and take off.
It is a known fact that drivers do not readily embrace change. Driver training is a must. Drivers are born with misconceptions and incorrect perceptions when it comes to almost any component on trucks and fat, funny-looking tires are prime targets. If the driver is not provided information about these tires, what to expect and the benefits they provide, I will guarantee that he or she will find problems with them and demand that they be removed.
The major concern that drivers have is the stability of a tractor and trailer if the tire suddenly loses pressure. Michelin conducted much testing in this area in association with Freightliner and produced a video that shows the effects of deflation in less than a second. Not only does the truck behave normally, but the driver can stop it easily and maintain control even if both drive tires on the same side deflate at the same time.
The test was done using a loaded flatbed with a high center of gravity as well as with a filled, unbaffled tanker just as the truck was entering a corner-which would be positively the worst-case scenario.
With this concern addressed, there is no reason why fleets should not investigate the use of new generation wide base tires that can save them weight, save them fuel, reduce tire labor, provide smoother ride and better handling as well as reduce their tire costs.
This tire will not be for everybody, but everybody should be taking a second look at it.
Peggy Fisher is president of Fleet Tire Consulting, based in Rochester Hills, Mich.