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With tires being the second-largest fleet maintenance cost next to fuel, fleet managers need to keep a close watch on how their tires are performing. Maximizing tire removal mileage, minimizing tire related roadside service calls, keeping tires properly inflated to improve fuel economy and keeping the casing in excellent condition to improve retreadability are all common goals of most every trucking fleet. Let’s take a look at some of the most frequent questions fleets tend to have regarding their tires.
1. How frequently should tires be checked for inflation pressure?
It depends. The determining factor is your specific service vocation. Do your vehicles spend most of the time running in pure line haul on the interstates from coast to coast or in the city in pickup and delivery operations? Are you going on secondary roads?
Tires tend to attract a high number of tread area punctures in pickup and delivery service. Running off highway will also cause tire damage and punctures. The more your vehicles are in service conditions that make them prone to punctures, the more frequently tire pressure checks are required. It may be best to check tire pressures daily for city, high-turning operations, compared to weekly or even monthly pressure inspections for pure line haul service. Maintaining proper tire inflation pressure is the single most important factor affecting tire performance.
Checking tire pressure using a calibrated pressure gauge is critical. Stick gauges, even when they are brand new out of the box, are only accurate to plus or minus 3 PSI.
2. What is the recommended tire inflation for my fleet’s tires?
In the old days, most fleets chose a single tire pressure for steers, drive and trailer tires. Why? Because it was easy for the mechanics and drivers to recall one number. One-hundred PSI was the magic number for a majority of fleets. This, clearly, was not the recommended procedure. Recommended tire pressure is based on the worst-case load the tire sees in the real world. Air is what carries the load. The tire makers publish load/Inflation tables that list the proper tire pressure based on a given load. The recommended pressure is also dependent on if the tire is running as a single or a dual configuration. In many scenarios, steer tires may require 110 PSI, drives 100 PSI and trailer tires 90 PSI. Choosing the recommended tire inflation pressure based on your loads will ensure a proper tire footprint, which will greatly enhance tire removal mileages.
3. What is the recommended tread depth pull point for my tires?
The DOT legal limit is 4/32-in. remaining tread depth for steer tires and 2/32-in. for drives, trailers and dolly tires. However, running tires down to the legal limit is not in the tire casing’s best interest. Tires running with low tread depth are more susceptible to tire cuts, tears and punctures, especially when the tire is running in the rain. Damaging the casing will adversely affect the tire’s retreadability. Keeping the casing in excellent condition to ensure that it will survive the retreading process should be near the top of any fleet manager’s list of tire priorities. Retreads typically cost one-third to one-half the price of a new tire. Setting your fleet pull point in the 5 to 7/32 range will protect your tire casings from damage.
4. What should my drivers look for on tires and wheels during their daily vehicle walk-around?
Driver walk-around checks are the early warning indicator for any tire and wheel issues, starting with air pressure. While the drivers usually do an inflation check on steer tires and may inspect a few drive tires for pressure, trailer tires are often neglected in the process.
In addition to tire pressure, running your hand across the tread surface from side to side will reveal any indication of irregular wear. If tires are not smooth with even wear across the tread surface, then there is probably an issue with the tire and/or the vehicle: Vehicle alignment may be out of specification; the suspension parts may be worn; or the tires may have been running underinflated for a long period of time. Drivers need to notify maintenance when tires are not running smoothly and evenly.
Checking tires for proper tread depth will help ensure that you are not running your casings down too far leading to casing damage. Inspect sidewalls for any impact breaks, and inspect wheels for any signs of cracks or damage.
Working with your tire professional to put together a step-by-step tire and wheel inspection for drivers will go a long way to ensure that you have the best tire program and lowest cost.