While TPMS — typically a low-pressure warning — has been required in new U.S. vehicles under 10,000 lbs. since Sept. 2007, such systems aren't required for heavy trucks. Perhaps that's counterintuitive, given the additional mass and weight of commercial motor vehicles and potential consequences and costs of a blowout. A primary factor in requiring TPMS in passenger cars was safety.
"Keeping your tires properly inflated will improve safety for your fleet. Under-inflation causes tires to wear faster and increases the likelihood of a blowout," Additionally, underinflated tires increase stopping distances and reduce handling capabilities of your equipment."
"Safety involves not only protection of our assets but protection of people's lives," Thompson points out. "The last thing you want as a fleet owner is a vehicle with your name on the side of it being shown on the news because it was involved in an accident or lawsuit."
Underinflated tires cost your fleet money. U.S. Dept. of Transportation (DOT) have shown that every 10 psi of under-inflation in a commercial tire causes a fuel economy drop for the vehicle of half a percent.
"Further, 53% of tractor tires are at least 5 psi underinflated, while 57% of trailer tires are at least 5 psi underinflated," citing DOT data. "Each psi of under-inflation is causing a fuel economy drop."
While fuel is a top cost for fleets, "more consumption of fuel creates more emissions," Thompson says. "Underinflated tires also create more consumption of natural rubber, because your tires don't last as long. So that's also a reduction of a natural resource."
"As any of our service people will tell you throughout Continental, the number-one issue that we get called in to fleets to listen to why they're not happy is irregular wear on their tires," Thompson contends. "And the number-one reason for irregular wear is typically air pressure-related, and it's more likely going to be under-inflation than over-inflation."
"I promise you, most likely all of your steer tires are 10% underinflated at some time or another," he adds. "That's almost a guarantee, particularly as axle weights have gone up and more and more vehicles require an H-rated or 16-ply steer tire."
Not only can under-inflation cause irregular wear, it can damage tire casings and preclude re-treading. "One of the main reasons that casings get rejected at a re-treader is for bead damage, which is typically related to overloading — and overloading is the same thing as underinflated," Thompson points out. "The amount of load that a tire can carry is directly related to how much air pressure is in that tire."
"Often, people think that they have the correct amount of air in their tires, but they haven't taken the time to scale their trucks out and compare that to the load and inflation tables that are provided by all tire manufacturers and make sure that they have the proper air for that load," he says.
"Nobody should be surprised that 67% of road calls are related to tires, followed by batteries, starters and other the other parts that fill up the remaining 33%," And when fleets have to deal with roadside calls for a blowout, they'll face the cost of the service, the tire casing is likely toast and interrupted drivers who aren't making money won't be happy about it.
But there's even greater potential loss, "What about the costs related to lost business? I'm working with a car hauler right now that lost a huge account related to delivery issues, and it's had a big impact on their business — so road calls can directly lead to lost business."
It takes real time for drivers to go around and check the pressure in, say, 18 tires, and that's time where they could have already been on the road and earning, and closer to a delivery. So that's all money lost that a TPMS could eliminate.
"Checking tires is expensive, and it's terribly inaccurate if you're checking tires with a tire gauge," "Even a brand-new tire gauge out of the box is only going to guarantee an accuracy of plus or minus 3 psi; most electronic tire pressure sensors are going to guarantee reliability within less than 1 psi. So they're more than three times more accurate than a hand-held gauge."
"And by the way, that's before that hand-held gauge has gotten dropped or gotten dirty and all the things that happen in someone's back pocket," he adds.
among other things, tire temperature as well as pressure. That can be a critical piece of information in terms of tire life.
"Over-temperature is the true death of a commercial tire," "If you look at an overloaded tire, you'll see a hard, brittle bead on that tire. That's due to excessive heat. If you've ever experienced a zipper rupture or heard someone discuss that, most people will tell you it's related to under-inflation.
"We point out that under-inflation creates excess heat in the tire. It's the excess heat that causes the tire to destroy itself, not actually the under-inflation," he continues. "Yes, under-inflation causes deflection in the sidewall, and that builds up heat. But it's the heat that causes the rubber inside the tire to break down, and it's also what causes the wires in the tire to snap."
On that note, uses an analogy of bending a coat hanger back and forth a number of times; at some point, the hanger will break. "And if you touch it where it snaps, you're probably going to get burned," he explains. "That's the same thing that's happening in the sidewall of an underinflated tire as it goes down the road."
"Whether it's your maintenance manager, your dispatch team or the owner of the fleet, we want everyone to be on the same page," So it's important not only to get data and alerts about improper tire inflation in your trucks, but to know what to do about it.
"You want to take that information and turn it into a tool," "You can contact the driver, contact the maintenance team. Let's say your vehicle is 1,000 mi. from home; let's say your dispatch team contacts that driver and says, "More importantly, if it isn't addressed, now you know," he continues. "So you can increase driver accountability and maintenance team accountability."
And a TPMS integrated with your fleet management system can record and present data over time, showing alert information and tire health across the fleet. Thus, the fleet could start to look at tires in a proactive manner, much as proactive maintenance is being applied to other parts on trucks to monitor and intervene before breakdowns.
As fleet management systems themselves continue to evolve and become more sophisticated, this last benefit of a TPMS could well be the most significant, so keep that in mind as you're shopping and doing your homework.