Ensuring that the tires on a fleet of school buses are in good condition should be an essential component of an operation’s maintenance program for the buses to run smoothly.
“Every school district or bus fleet should have some kind of tire management program,” says Doug Jones, customer engineering support manager for Michelin Americas Truck Tires. “A good program includes cradle-to-grave tracking, analysis, preventive maintenance and more.”
Industry professionals offer numerous tips specific to tire maintenance, touching on inflation and pressure, axle alignment, tread depth and mounting. They also offer insight on how often tires should be inspected and signs that a tire needs to be replaced or repaired.
Taking into consideration this information will equip both drivers and technicians with the knowledge to help prolong the life of a tire and avoid problems when buses are on the road.
Establish proper inflation and pressure
Determining whether tires are properly inflated is the first item technicians should check for. Scott McNamara, a trainer for Bridgestone Bandag Tire Solutions, says that the air pressure of all tires should be checked and corrected weekly with an accurate inflation pressure gauge.
“Tire pressure should be checked while the tires are cold,” he adds. “Do not bleed air from tires while they’re hot as this will result in under inflation. Operating on an improperly inflated tire will create severe tire damage.”
Thomas Kenny, manager at Hankook Tire America Corp., elaborates, saying that improper tire inflation can result in shorter tread life, irregular tread wear and degraded durability, along with decreased fuel economy and degraded vehicle handling.
Moreover, Timothy Miller, senior marketing specialist for Goodyear Tire & Rubber Co., notes that the pressure in tires should be kept at a level that will support the load that the bus is carrying.
Officials at Double Coin suggest reviewing a bus’ owner’s manual or the vehicle load and tire information placard. These items provide data on the weight of the vehicle and the standard load, helping to determine the air pressure level.
Monitor axle alignment and tread depth
Miller says that attention should also be given to a bus’ axle alignment. If tires come in contact with curbs with the potential to knock the axles out of alignment, the alignment should be checked at each tire change. Steer axles should be checked for proper camber, caster and toe settings. Drive axles should be checked to determine whether they are perpendicular to the chassis’ centerline so that the bus will travel straight.
“Technicians should establish a minimum tread depth allowed before tires are changed,” Miller adds. “This could vary from location to location. Buses in northern Michigan might require deeper tread depths to travel in snow and slush, but buses in Miami might be able to run until the tread is down to 4/32nds without any problems.”
Avoid mixing tire types, brands
Manufacturers and technicians also have suggestions for mounting tires on a bus. Officials at Double Coin and Brad Barker, shop supervisor at Park City (Utah) School District, both caution against mixing tires. “Try to match brands, types and tread designs on each axle and avoid mixing tire brands and types. Each tire has its own flex characteristics,” Barker explains.
John Whelan, heavy-duty mechanic/lead hand at School District #73 in Kamloops, British Columbia, offers specific advice on dual tires, saying that these tires should be the same size and have the same tread pattern.
“Irregular duals will cause one tire to work harder and heat up, causing premature wear and possible failure on the highway,” Whelan says. “A rule of thumb is that the diameter of both tires must not have more than half an inch difference, while there should be no more than a three-fourths inch difference in the circumference of the two tires.”