While National Tire Safety Week has passed, there are several excellent points that truckers must keep in mind. Tire safety is a critical aspect of operating a commercial motor vehicle (CMV).
Today, we are going to look at three different aspects of ensuring the most important part of your ride – the wheels – stay in good condition and ready to roll!
The first of each of these is tire pressure. There are so many different aspects of tire pressure that impact both fuel economy and safety. Let’s take a closer look.
Keeping Tire Pressure in Mind
If you aren’t already familiar with the fact that 10 percent under-inflation can cause a 1 percent drop in fuel economy, your shop technician isn’t keeping you properly informed. Softer tires have an increased rolling resistance, so it is important to ensure they are always properly inflated.
But here’s a question for the experts to consider: What if all 18 tires were under-inflated. Would it still equal a decrease in fuel economy of 1 percent? The consensus is that most or all of the tires need to be underinflated in order to see a drop in fuel economy.
One of the main reasons for this is that the overall fuel economy really depends on the axle position of whichever tire happens to be underinflated. Drive and trailer axles have a much greater impact on fuel economy than wheels in the steer position.
Is your fleet paying close attention to tire maintenance? It isn’t just anecdotal, there have even been European studies conducted determining that fleets aren’t taking tire pressure maintenance as seriously as they should.
The official industry recommendation for any fleet tire can be found on the Load & Inflation Tables (LI&T) found through the industry association affiliated with the tire maker. Minimum tire pressure based on the load will always be provided.
Tire manufacturers consistently maintain the load tables to ensure safety is always a top priority. When a tire is at minimum pressure, you can expect it to operate at a lower than normal threshold for its given capacity.
One thing to also keep in mind is reconciling what the L&IT says with how the fleet is operating the vehicle? Although operating at 90 percent even if the L&IT is requiring a minimum of 90, is that 10 percent underinflated? Not necessarily. If the fleet is running at 100 psi, then 90 percent still puts you at the acceptable threshold.
Still, ensure you are properly servicing your tires. Tires consistently at 90 psi or less might be leaking or be ready for a servicing. You don’t want to be running underinflated on a constant basis, especially considering the vocation of the tire.
While this might clarify whether a tire is underinflated, the other question remains: fuel economy. Are fleets giving up on fuel economy if they ignore the issue of underinflation?
When a fleet consistently runs lighter loads, they may see some wear benefits when underinflated. For lighter loads, the tire’s softer contact patch accounts for more even wear.
Underinflation still causes problems. As tires flex more running down the road, it can hurt overall fuel efficiency. The vehicle is forced to work harder when the tires are underinflated.
Does fuel economy trump tire wear? These days, for most fleets, the answer is yes.
Paying Close Attention to Alignment
Did you know that only a small percentage of overall fleets do regular alignment maintenance on their vehicles? Instead, they will wait until it is obvious an alignment is needed, then perform the vital function. The problem is, by then damage has already been done, whether it be an annoyed truck driver or a pair of chewed up tires.
Consider that if an alignment is done before it becomes obvious the truck needs one, you may get longer life out of your tires. Tires can’t be pushed down the road at whatever angle and not potentially suffer some damage or irregular wear patterns.
As we had just been discussing them, the tires will tell you the full picture. If you see excessive wear, whether on the opposite shoulder or any other type of tire feathering, it’s time to consider looking at other mechanical conditions – not always the obvious ones, perhaps.
Also remember that when we talk about alignment, we aren’t just talking about tire position, we’re also referring to axle geometry. Drive axle or even trailer axle problems can be big indicators of an alignment issue.
Even when a truck mildly needs an alignment, the truck driver may not immediately notice it. These things can happen on such a small fraction of a level that the trucker is countering their slight push without realizing it. Over time, this will cause a specific wear pattern on the tire.
There are two specific conditions your fleet technicians should be keeping an eye out for:
- Toe-in Wear: The inside of the tire shoulder wears prematurely
- To-out Wear: The outside of the tire shoulder wears prematurely
Conversely, if you find that both the left and right steer tires have the same wear pattern, you may want to consider taking a second look at your drive axle alignment.
The first place you can typically spot an alignment problem is on the tires, an apt point considering we were just discussing them at the beginning of the article.
Finally, you want to make sure you always keep an eye on your trailer alignment as well. Those tires can become misaligned and suffer the same kind of wear patterns, just for different reasons than drive or steer tires.
One thing we hope you’ve noticed as we go through these individual sections of your CMV that these systems are all interrelated. We are going to put a capstone on that method of thought by covering your CMV fleet’s tire and wheel balancing program.
To Balance or Not to Balance: That is the Question
First, let’s dispel some myths. Many still believe that wheel balancing may not always be necessary. As a matter of fact, it’s typical this critical function may fall by the wayside during shop time.
Before the tire guys got good at making tires, balancing was an absolute must. Some believe that now we don’t really need to pay attention to it. They think we are living in the age of the state-of-the-art tire.
In many ways, we are, but there is plenty of information out there validating the need for proper wheel balancing. It has been proven to help keep specific types of wear from showing up on your tires. Furthermore, it could contribute to misalignment on your steer axle if ignored.
Still, the argument is made that a fleet can eliminate the need to have a tire balanced if you ensure they are installed properly to begin with and maintained well in the shop and on pre- and post-trip inspections.
Those who make this point mention a guideline for inspecting and mounting procedures within the American Trucking Association’s Technology and Maintenance Council Recommended Practice library. The notation? RP214D. Properly sanctioned, does this mean you don’t ever to have to balance your tires again?
Some choose to balance tractor, but not trailer tires. Your fleet technician should know how much weight to balance on the tire before it might need to be deflated, broken and rotated.
Just ensure you are properly investigating truck driver complaints. If a truck driver makes a mention of a vibration in the column, it may be cringe-inducing, but also a sign to check on a potential problem.
Never use balancing a tire to mask another problem. Be sure you are doing a proper investigation before you make a qualified stab at the problem.
How to Balance
Fleets have an array of balancing technologies at their disposal. Whether it be through internal balancing compounds built into the tire or balancing rings that sit between the wheel and the hubs.
Imagine a time when fleets used something like a golf ball balanced on antifreeze. We’ve come a long way since then and fleets have a greater amount of choice in how they balance their tire.
You can also utilize balancing weights, which can be installed when the tire is first mounted onto the wheel frame. Unless something untoward happens, the weight should last through the life of the tire.
As lead is phased out, some municipalities are turning to other substances to meet regulatory weight manufacturing compliance. A couple substitutions include compound combinations utilizing things like zinc and steel.
Want to know more about how balancing benefits your fleet? Read TMC’s latest S.11 Energy Conservation Group Study. Newly updated, it offers you a notation advising on the documentation proving you can save up to 2.2 percent on Type II fuel by ensuring all 18 tires on your rig and trailer are balanced.
In the end, whether we are talking about safety, fuel economy or just-plain good business, properly taking care of your tires and keeping your vehicle alignment in mind should always be at the top of your shop’s maintenance list.