Brad Barker is shop supervisor at Park City (Utah) School District.
Choosing tires that are well suited for the buses they will be mounted on and the environment they will be operating in is as important as making certain that the tires are in good condition.
Goodyear offers two tools to help customers choose the best tires for their applications.
“TVTrack helps track tire performance, and TireValuCalc can help calculate the total costs of running various combinations of tires to help decide if certain tires offer cost-saving advantages over other tires,” Goodyear’s Timothy Miller says.
Both tools are available at www.goodyear.com/truck/fleethq/fleet_tools.html.
Brad Barker at Park City (Utah) School District encourages technicians to run tests on tires to determine which are best to meet their needs. “Data to gather includes the vehicle number, meter readings (miles) at the time of installation, the date of installation, the tire brand and model number, the tread depth when the tire is new and the position the tire was installed in,” Barker says. “Also, record the price paid for the tire. This will be used to calculate costs per mile and cost per 32nd inch of tread.”
During the test, watch tire wear. At each preventive maintenance session, tire rotation may be necessary to maintain even wear and to obtain the highest mileage.
Rear traction tires may start to heal and toe. If this occurs, rotate the tires side to side so that the rotation direction is reversed. This applies to directional tread designs as well, Barker says.
Steer tires will sustain different types of wear, typically wearing on the right-hand, outside rib first.
“This occurs due to turning differences between left- and right-hand turns. Right-hand turns are almost always slower and sharper, so there is less side to side scrub on the tire with the slower speed. Left-hand turns are usually wider and faster,” Barker explains.
Turning left wears the tire on the right-hand rib on left and right steer tires, and it wears the tire from the right to the left. This wear pattern should be monitored closely. It is not uncommon to rotate front steer tires side to side during every oil change to keep this issue in check.
When the tires have worn out, Barker recommends recording the lowest tread depth on the tire that is being removed, then subtracting this measurement from the tread depth that was recorded at installation. You can then calculate costs per mile, cost per 32nd and miles per 32nd from the other data recorded earlier.
“Do this for every tire installed on a bus. After some time you will begin to see which tires are performing best,” Barker says.
To discuss the tire test or other maintenance issues with Barker, visit his Website, www.theschoolbuspm.com, or the Professional Garage forum on Schoolbusfleet.com.