Speed, usage specs
Be sure you know the average speed that the vehicle will run. Speed has an effect on tire carrying capacities. For tires that will be running over 65 mph, the load and inflation tables may require an increase in inflation pressure and a reduction in carrying capacity to prevent harmful heat buildup.
Some tire manufacturers have rated their tires for speeds at 75 mph or above without adding pressure and reducing load. Other manufacturers have not. Make sure you take this into account if your fleet customer's vehicles are routinely operating over 65 mph. (The chart on page 12 applies to tires that have not been rated by their manufacturers to operate at 75 mph or above.)
Next, make sure you know what type of operation the vehicle is going to run in: line haul (also known as long haul) and regional (also known as short haul) over the road; urban pickup and delivery (also know as local); or on-off road.
Line haul trucks normally make runs that exceed 500 miles, regional carriers operate within a limited multi-state area such as the Midwest, Northeast, etc., and have runs of about 250 miles and pickup and delivery fleets operate just in their local area.
Vocational trucks in on-off road service run both on highways as well as go off paved roads.
Tires designed for over-the-road operations are compounded and designed to produce high tread mileage and low rolling resistance for improved fuel economy. They are produced with long-wearing compounds and tread patterns that are resistant to irregular wear.
Deep tread patterns are provided on drive tires to get maximum mileage and shallow tread depths are designed for trailer tires to further minimize irregular wear.
Urban tires are specially designed to address the hazards that pickup and delivery tires encounter daily. Their treads are specifically compounded for high turning, low mileage applications that are resistant to punctures and other road hazards.
They also are designed to provide good wet traction and resist oil contamination frequently encountered in urban use.
Their sidewalls are designed to minimize damage from curbing and have special protector ribs to absorb shock and protect the sidewalls from damage.
Know a fleet's needs
It is important to select the right tire for the fleet's operation.
Mixing tires in the wrong applications is not smart and would defeat their purposes.
Over-the-road tires used in urban operations would tend to fail prematurely due to sidewall abrasion and road hazards. Their advantages of high mileage and fuel efficiency would not be attained.
Urban tires on the other hand will not perform well over the road, either. They will wear out quickly, run hot, be prone to separation and consume fuel. Their advantages of scuff and penetration resistance would not be utilized either.
However, there also are tires designed to work in multiple service applications for fleets that operate their vehicles in combinations of these routes, such as regional and local.
Although these tires will not perform as well as the tires specifically designed for a particular service vocation, they're a good compromise for multi-duty vehicles.
Different tire types and sizes may require different wheel rim widths. Most tire sizes have two or three approved rim widths.
All tire manufacturer data books list the ``design'' rim width as well as any optional rim widths. A narrower rim offers lighter weight and increased vehicle clearance but may contribute to reduced tire life due to the ``crowning effect'' on the tread.
Vehicle stability and traction could be reduced under certain conditions. The narrower rim usually does not have as high a load-carrying capacity as a wider rim.
A wider rim may increase vehicle stability by spreading the tire beads, flattening the tread and straightening the sidewalls. The wider rim usually has a greater load-carrying capacity and may provide greater resistance to rim flange wear.
Be sure when selecting a tire that the appropriate wheel has enough load-carrying capacity.
Sometimes the wheel load capacity is less than the tire's and is not enough to carry the anticipated load. If this is the case, a different tire and wheel combination may have to be selected.
Before the final word
Before making your final tire recommendation, there are a few other management considerations that you and the fleet should take into account.
Many of these are especially important when spec'ing new equipment:
* Availability of the tire selected;
* Tire purchase price vs. performance (cost/mile);
* Effects of non-standardization in fleet;
* Additional inventory costs and space requirements;
* Effects of tire down-sizing on vehicle gearing and braking;
* Timing/scheduling for phase-in or change-over programs;
* Added training for maintenance personnel and/or servicing vendors;
* Retreadability and repairability; and
* Legal or contractual (lease/trade in) requirements that the fleet may be bound by.
As you can see, selecting the right tires for a fleet operation can be difficult and complex-which is why your customers will look to you, their tire expert, for assistance.
With thousands of fleets buying hundreds of thousands of trucks in the next three years, you're going to be very busy.
Peggy can be reached via e-mail at [email protected]