In contrast to the automotive market, changes in the size of commercial truck tires tend to evolve slowly, and are more dependent on end-user demands. A number of factors should be taken into account when we try to predict how commercial tires of the future will differ from those on the market today.
To begin with, there are the limitations imposed by related axle-end and driveline hardware. And not to be underestimated is fleet resistance to new products unless suppliers can convincingly demonstrate both cost benefits and long-term durability. Some key areas of consideration are:
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Life cycle costs;
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Required changes to related driveline components;
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Brake system hardware compatibility;
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Net change in dock height, overall vehicle height, and underside truck/trailer ground clearance;
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Axle use interchangeability (steer/drive/trailer);
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Emergency over-the-road availability;
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Effect on fleet component standardization and maintenance costs;
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Effect on vehicle trade/resale value.
Today's commercial trucks are products of considerable evolution — not just in basic design, but in many of the core components as well. Since parts and systems often come from vendors other than the vehicle OEMs, coordination of engineering, testing and compatibility is more complex and time consuming than it is in the car and light-truck industry, where manufacturers are more vertically integrated and accustomed to model-year changes that include major redesigns.
The new-generation wide base single tires for drive and trail axle positions provide an excellent example. Engineering review, and potential redesigns of wheels, hubs, bearings, axles, brakes, on-board inflation systems, and other components, will result in the optimized final system configuration. Much of the resistance to this change is removed by the fact that tire rolling diameters have been matched to the popular low-profile dual tire size, and that both drum and disc brake packages used with current duals are compatible with the wide single wheels. During a transition phase, however, most end users will want to retain as much of the time-proven componentry as possible to contain costs and protect resale value.
Standardization is another important issue. Modern OTR trucks use many components that are readily available from a variety of vendors. This tends to contain maintenance costs, minimize downtime, and attract the largest used-truck purchaser base at resale time. Deviation from these “popular spec” components needs to be justified by service condition requirements or cost benefits that will occur in an acceptable payback period.
One example is the use of 19.5-in. tires on auto transporters. Non-standard brake packages, wheels, axle ratios, and other components are required, but resale value is a low priority since these specialized vehicles have very long lifecycles and are resold to limited market. The productivity considerations of transporting taller vehicles (SUVs, for example) within legal height limits, as well as ground clearance requirements to safely negotiate railroad crossings, define the height envelope dimensions of which these tires are an integral part.
The bottom line is that to a large degree truck tire design in North America is driven by the end user, with productivity and lifecycle costs their most important concerns. This helps control transportation costs, ultimately making our products more competitive in the world marketplace.
