The biggest challenge ensuring that you maximize your tire life is maintain proper inflation. According to Tiona Campbell, program manager for the Hendrickson controls business unit, underinflation is the biggest threat to tire life. Underinflation results in sidewall deflection, which generates excess heat and, in turn, weakens the internal tire structure, called the carcass. When it comes to drive and trailer tires, Campbell explained that dual tire configurations are designed to share the load equally. “They should be the same size and diameter and have the same tread pattern,” Campbell said. “Equal inflation pressure is optimal but tire manufacturers recommend that they are at least within 5 PSI of each other. However, research indicates that reality is quite different.
“Testing shows that a 5 PSI difference between duals creates a 5/16-in. difference in tire circumference. This means that the larger tires essentially drags the smaller for 13 ft. every mile. This can lead to rapid and irregular wear of the smaller tire, while also inducing internal damage to the larger tire, which can also lead to premature wear.”
Too much air
Even though underinflation is a tire’s biggest foe, that doesn’t mean that you should put a little extra air in the tires to compensate. Overinflation can be just as detrimental to your tire life.
“Overinflated tires are harder than properly inflated tires, making them more susceptible to tread surface cutting, punctures and impact breaks,” Campbell said. “Overinflation changes the tire’s footprint causing the tire edges to pull away from the ground and only make contact when they skip across road imperfections. That scuffing of rubber causes rapid and irregular tire wear that can cost 7% to 15% of the tire life.”
According to Campbell, the most common reason for overinflation is elevated tire operating temperatures combined with increased ambient air temperature. “Although tires are designed to function with pressure variations from warming during normal use,” Campbell said, “pressure effects resulting from ambient temperature fluctuations are a different story.”
Tire inflation systems can go a long way in maintaining a constant air pressure, but you’ll want to make sure that your system of choice has an equalization ability. Hendrickson’s Tiremaax Pro, for example, is capable of active inflation, relieving and equalizing tire pressure. The system detects pressure dips below a preset level in one or more tires and directs air from the trailer air supply to the affected tires. The system also responds to changes in outside temperature and prevents over-inflation by relieving air from the tires back through the supply lines and exhausting at the controller. This, Campbell said, is an important feature because ambient air temperatures can impact tire inflation systems.
“Tire inflation systems that are only capable of inflating tires will add air pressure to tires anytime the ambient air temperature drops,” Campbell said. “This includes low-temp extremes to which the vehicle is exposed. When the vehicle returns to a warmer environment, the pressure in the tires increases above the target pressure. The increase in pressure caused by both use and ambient temperature typically cannot bleed off at the same rate that it increases.”