Inspection Practices
Train your drivers to perform their pre-trip inspections religiously – and that includes checking the tires and the spare.
Evan Lockridge
Contributing Editor
Want to get better fuel economy, longer tire life, reduce the risk of roadside tire repairs and delays – as well as avoid the resulting chewing-out from customers?
Make sure you have a good tire inspection program in place.
Drivers should be trained to perform pre-trip inspections religiously – inspections that include each tire, as well as the spare, according to Bridgestone/Firestone.
Of course there is no way to guarantee this will always happen, so any time one of your fleet's technicians works on a truck is an excellent opportunity to check on the tires. Technicians should examine tires for cuts, bruises, cracks, bulges and penetration. If damage is found, have the tire examined by a qualified tire professional. Keep in mind that the sooner you repair a damaged tire, the less likely you'll have to send it to an early grave.
When inspecting tires, you also need to keep an eye on tread depth. Federal Motor Carrier Safety Administration Regulations require tractor-trailers to have on the front wheels "a tread groove pattern depth of at least 4/32 of an inch when measured at any point on a major tread groove."
All other tires on the truck should have a tread depth of at least 2/32.
Air pressure checks are perhaps the most important part of regular maintenance. If one tire seems to have a constant appetite for more air, it's reasonable to assume the tire has been running with too little air when it's on the road – and that's not good. Under-inflated tires are one of the biggest causes of roadside tire emergencies.
Have such tires examined by a trained technician as soon as possible to determine the cause of the air loss and check for any damage to the tire. According to Goodyear, any tire known or suspected to have been run at 80 percent or less of normal operating pressure could have permanent structural damage to the steel cords. This damage can lead to a dangerous zipper rupture in the tire's sidewall when on the road.
In addition to inflation, there are some things technicians can look for in the course of regular tire inspections that may be symptoms of other problems on the truck, or of poor driving or maintenance practices.
The Technology & Maintenance Council of the American Trucking Associations recently published a new edition of its Radial Tire Conditions Analysis Guide, which is a comprehensive guide to tread wear and tire conditions.
For instance, according to the book, excessive wear across one shoulder of a steer tire could be a sign of an alignment problem, or of damaged or poorly maintained steering components.
If you spot excessive wear on one side of the steer tire extending from the shoulder toward the center of the tread, check drive axle alignment. Worn kingpins, improper bearing adjustment and excessive axle loads can also cause this.
Feather wear – where the tread ribs are worn high to low on each rib across the face of the steer tire – is another sign of misalignment, or of suspension problems, bent tie rods or other chassis misalignment.
Inner rib depression wear on the steer tires, where one or more inner ribs are worn below the level of the adjacent ribs, is usually a sign of low air pressure.
On drive tires, if you spot heel/toe wear (each lug around the tire is worn high to low from the front to back edge), you're probably looking at mismatched inflation pressures or tire diameters on your dual assembly. Same thing if alternate lugs are worn to different tread depths around the tire circumference.
A flat spot on the tread surface of a drive tire, called brake skid, can be caused by new brakes, an unbalanced brake system, or over aggressive use of the brakes.
While you're looking for problems such as these and others, it's also a good time to inspect a truck's wheels.
"You want to check for cracks or damage, missing lug nuts, broken studs or rust streaks extending from any hand hold or fastener, which may indicate loose nuts," says Dale Overton, field engineer for Accuride Wheels.
Also important, Overton says, is to check for a variation of the number of threads sticking out from the end of the nut on the wheel. For instance, if you have three threads sticking out from all of the nuts but one has only one thread sticking out, that may indicate the nut is not fastened down far enough. If more threads are sticking out past one nut than the rest, you may have a bad fastener that's been stretched.
While regular inspections of your tires and wheels may often turn up nothing, performing them can save you money and spare you from delays and other headaches.
