Fleet productivity is important. Indeed, it is one of the founding pillars of a successful trucking business. Motor carriers and owner-operators are constantly looking for new ways to reduce costs and raise uptime. While fleet technicians focus on the conditions of their tractor tires, what are they doing about their trailer tires?
Did you know that tires are one of the top ten expenses in the trucking industry? Lower your expenses by maintaining tire pressure and life-cycle. You can save many thousands of dollars each year by ensuring your tires are neither underinflated or overinflated, mismatched, or damaged. It is important that you come to an informed decision when you are spec’ing both trailers tires, and tire pressure management systems.
The Number One Trailer Breakdown Problem
Ask any fleet manager and they won’t need a statistic to tell you that the number one reason trailers fail is because of tire issues. As a matter of fact, 48 percent of road calls are the result of blown tires or other tire related issues. Yet, mismatched duals account for a decent share of problems as well.
In fact, the North American Council for Freight Efficiency (NACFE) came to some alarming findings where trailer tire operation is concerned. One in five trailers are operating with tires that are over-inflated by at least 20 pounds per square inch. Even worse, three percent of all trailers operate with four or more tires under-inflated. As if that weren’t bad enough, another three percent are operating with tires that are under-inflated by at least 50 pounds per square inch or more.
Statistics put together by the Technology & Maintenance Council’s Tire & Wheel Study Group also revealed some startling numbers. Nearly a fourth of all tires surveyed were over-inflated by more than 20 psi. In the truckload sector, nearly seven percent of all tires were under-inflated by 20 psi or more. In this category, underinflation of this type can be very dangerous.
So, what’s the problem? Why is over-inflation such a persistent issue within the trucking industry? Over-inflation isn’t always the problem of truck drivers or maintenance technicians putting too much air in the tires. Generally speaking, over-inflation is the result of elevated tire operating temperatures and an increased amount of ambient air temperature around the tire’s sphere of operation.
Always consider that the TMC RP 235 explicitly states that tire pressure can rise by 10 to 15 percent when ambient temperatures are high. Tires are manufactured to function within specified parameters during normal use and warming situations.
Elevated tire temperatures do not bleed off at the same rate as natural air loss. When diffusion is taken into account, psi only drops around 1 to 2 per month. This is when over-inflation becomes a problem. Over-inflated tires are more susceptible to tread surface cutting, punctures and other impact breaks.
Fleets must also be aware of a tire’s footprints. When over-inflation occurs, it changes the physical nature of the tire itself. Irregular wear patterns are generally the cause of over-inflation, whether the changes be on the shoulder ribs of the trailer tires or otherwise, edges of over-inflated tires pull away from the ground and make harder impacts when they skip across road imperfections. Different types of scuffing merely aggravates irregular wear. What happens when irregular wear becomes a persistent problem? You could lose up to 15 percent of your tire life.
Mismatched Duals Are a Problem
Trailer tires that are arranged in a dual configuration are meant to share the load equally between each other. It is critical that they are both same size and diameter, as well as have the same tread pattern. Although the rules say you are generally okay if they are within around 5 psi of each tire, the reality of that situation can be quite different.
Studies show that most of the time, nearly a fourth of all trailer tires had mismatched air pressure where a pressure difference was greater than 5 psi. The problem is exacerbated with dual setups. Mismatched duals is not always easy to spot. Yet, within a short period, mismatched duals of varying pressures can create major irregular wear pattern problems.
When you combine different psi levels with mismatched duals, say even of the tiniest circumference, the results are dramatic. A tire generally completes around 450 – 500 revolutions per mile. If one tire is smaller than the other, it will seemingly drag against the pavement and rapid irregular wear will result.
The larger tire will also show problems, as it bears the brunt of the load and develops internal damage from breaking force. Height problems combined with braking force problems can lead to a dangerous combination. It is extremely important that dual tires are neither mismatched nor suffering from inflation issues.
Common Tire Problem Associations
When you look at the real-world consequences of mismatched tires operating at problem tire pressure, it has a significant and immediate impact on the fleet or owner-operator. Just take downtime expense as one example.
Consider how many road calls are made because of tire problems. Now think about the average out-of-pocket cost associated with a tire-related rescue. Most estimates put it at around $800 – $1,000. That is no small amount of money.
When you consider unforeseen problems, such as distance, late freight fees, a hit to your reputation or a disappointed client – the costs rise dramatically. If a tire-related incident results in a major accident, injury, or fatality, you are also looking at huge insurance costs and potential litigation expenses.
In the case that there isn’t a major road failure or accident, mismatched tires or tires suffering inflation problems also cause a reduction in fuel economy. Up to 30 to 40 percent of the fuel used in running a large truck is used in overcoming the rolling resistance of the tire contact with the road. Increased heat creates increased fuel consumption and further compounds the problem.
Most fleet technicians will tell you that running a tire under-inflated by even 10 psi can decrease fuel economy by 1.5 percent or more. If you add up the numbers, that equates to nearly $500 per tractor-trailer per year in unnecessary fuel use.
Not only do under-inflated tires cause a problem for your bottom line, if you are going through a roadside inspection and have tire inflation issues, you could get hit with a BASIC violation. A flat tire alone is an eight-point deduction, while an under-inflated tire is a three-point deduction. When a tire inspector notices damage, it is usually the result of inflation problems.
Consider Greenhouse Gas Phase 2
It is important for all fleets, for many reasons, to consider Greenhouse Gas Phase 2 Regulations, but especially when it comes to tires. These regulations have renewed the focus on technology as being an effective method for improving fuel efficiency and reducing emissions. When fully phased in, fuel savings would be nearly half-a-million barrels per day in less than twenty years.
While the regulation itself is very large and can be difficult to wade through, the requirements where trailers are concerned is quite succinct and easy to understand. They say that all full and partial-aero box vans must meet a specific standard, whether it be through the use of low-rolling resistance tires, aerodynamics, tire pressure systems or other technologies. These standards apply to both reefer and dry-van varieties. Liquid and gas tanks, straight flatbeds, or non-aero box vans must meet the standard.
The fact is this: There are important considerations to be made when tire inflation is considered. Fleet managers and owner-operators must overcome the struggle to get a handle on proper tire inflation and dual mismatching. Making sure the right amount of air is in the tire at the right time is critical to saving on unnecessary tire expense and tire pressure issues.
The Front Line
Your front line of defense against tire problems is your truck drivers. They complete the pre- and post-trip inspections, do a visual inspection of all tires, and should be regularly checking tire pressure.
The next stop will be your shop technicians. They spend a lot of time examining your equipment, it is vital that they can quickly spot tire pressure or mismatch problems. Are they properly trained in spotting problems when they arise?
Finally, it is important to consider tire pressure monitoring systems for your operation. These systems provide a direct measurement of pressure and even sometimes the temperature of a tire. If there is a problem, generally an alert light will appear on the dash and alert the truck driver that there is a problem with the tires. Even better, these monitoring systems can be used on both tractor and trailer.
While you pay a lot of attention to the rubber that drives your tractors, you can never leave out what your trailers drive on. Without them, your freight goes nowhere. Always consider inflation and tire matching when training your truck drivers, technicians, and anyone else who is responsible for keeping an eye on your equipment.