Truck Tires for Work or Play
Truck tires for light- and medium-duty Class 3-6 trucks have historically been general-purpose offerings. This made perfectly good sense for many years as these vehicles, such as the Class 3 dually pickups, often served in personal-use applications.
Even most commercial uses, such as pickups and vans used by plumbers, electricians and farmers, were characterized by low annual mileage and maintenance schedules mirrored those of the passenger cars the owners drove during their off-duty hours.
On the other hand, Class 5-6 medium duty trucks tended to be scaled down versions of larger trucks, but built with low cost, standardized components. These were the last vehicles to abandon tube-type bias ply tires in favor of tubeless radials at original equipment. School buses accounted for a large percentage of these vehicles.
Notable exceptions were the medium duty Japanese and European import trucks that were often fitted with 17.5-inch tires. However, few of these Class 4-6 vehicles were sold into the North American market. Another exception were the one-way rental service trucks that often didn’t receive tire upgrades due to fleet manager concerns over security and a high incidence of damage caused by rental customers.
Rounding out this group are recreational vehicles (RVs), the tires for which are often replaced prior to wear-out simply due to old age and sidewall weathering from limited use.
New Times Means New Tires
Recent market changes have driven the emergence of two distinct families of tires for these Class 3-6 vehicles. For simplicity, let’s refer to the traditional general-purpose tires as “personal service” and the newer, upgraded tires as ®commercial service.®
Several factors have been strong influences in this market distinction. Growth in the package delivery industry, serving both residential and business customers, has accelerated dramatically. Further growth in this segment is assured because of expanding phone, mail order and Internet sales promising doorstep delivery to time-pressured purchasers. Fleets like UPS, Federal Express, and a growing list of others serve this market with an intense focus on productivity and cost-effectiveness, including truck operating cost control.
And, in recent years, other commercial truck operators have reevaluated their vehicle needs with an eye toward downsizing trucks whenever possible by more exact matching of equipment to job requirements. Utility service companies, state and municipal road departments and others are continuing this trend. Vehicle manufacturers have responded with new mid-size truck offerings. Nearly all are equipped with fuel-efficient diesel engines and a variety of beefed up chassis components.
Another driving trend is to larger, more powerful chassis developed for the very healthy upscale RV market. These units have gained weight, luxury features, reliability and durability compared to their predecessors. Many are powered by commercial service-based pusher (rear mounted) diesel power plants, and have been designed to use high load rated commercial service tires.
TMC Brings Change
Additional momentum for smaller sizes of new generation commercial tires has come from fleet maintenance executives working through The Maintenance Council (TMC) of the American Trucking Associations. TMC Study Group S.14 was formed in 1993 to address light- and medium-duty trucks specifically. The group is looking at how many of the fleet-cost-saving design and maintenance practices that had been perfected for larger Class 7-8 highway vehicles can be transferred to the smaller size trucks. A number of components, including transmissions, brakes, wiring systems and tires have already been addressed.
The resulting new commercial tires could easily be considered scaled down versions of larger truck tires, in contrast to light duty or personal use tires being viewed as scaled up versions of modern passenger car tires. When properly matched to service conditions and vehicle type, each offers advantages. However, the potential exists for user dissatisfaction and, in some instances, safety concerns if improper selections are made.
New Breed Mirrors Old
Most characteristics of the new “commercial tires” mirror their radial ply 22.5- and 24.5-inch big brothers. Nearly all are constructed with steel plies and steel belt packages, and have reinforced sidewalls to resist abrasions. They’re designed for multiple retreadings, and are compatible with the same repair procedures and materials used on larger truck tires.
Sidewall designs are black no raised white letters here ®” and tread designs tend to be high mass (the relation of contact area to void area). Manufactures offer all-position highway rib and drive axle specific highway tread types, both on a common casing size to simplify retread usage.
Selected sizes are also offered in more aggressive, usually deeper, on/off road designs often fitted to all-wheel-drive trucks in commercial service applications. The most popular rim diameters are 16-inch and 19.5-inch at present, with some 17.5-inch offerings.
The four most popular original equipment sizes for 1999 were: 225/70R19.5, 245/70R19.5, 215/85R16 and 235/85R16.
Always Check Size & Rating
Although some tire sizes are offered in both “personal service” and ®commercial service® types, available load ranges and therefore load ratings ®” may be different. Users should always check the vehicle manufacturer’s tire size and load range requirements. Also, both tire and vehicle manufacturers generally recommend against mixing tire types across an axle.
Any question or concern about proper tire selection or mixing should be directed to these sources. In certain cases, the higher load commercial tire designs also require special higher rated wheel designs, so retrofitting may not be a viable option. If in doubt, seek professional advice. It’s usually as close as the nearest phone or computer.
Over time, the continuing evolution of vehicle types offered by manufacturers and customer preferences for performance/cost relationships will ultimately determine penetration and size mix of the new “commercial tires.” They are generally more expensive at initial purchase, but provide lower life cycle operating costs in demanding service applications.
Meanwhile, tire dealers and truck users alike should be knowledgeable about the choices available.®′