Inflation pressure systems keep tires healthy but need attention themselves

A flat tire anywhere on the rig can delay a trip and cut into your income.

June 2020

Tom Berg


Tires are expensive, and your life is valuable, so you probably watch the tires on your tractor, especially the ones on the steer axle, and add air when needed and remove and replace them as necessary.

And you do the same if you also own the trailer you pull. If you contract with a fleet and pull its trailers, you might not worry as much about tires back there. Should that be the case, keep in mind that a flat tire anywhere on the rig can delay a trip and cut into your income. If that fleet runs tire pressure monitoring and inflation systems, you probably know that they warn of any problems and keep tires pumped up, which helps you almost as much as the fleet. If you own trailers, maybe you equip them with such a system.

Trailers get the most attention from developers of tire pressure monitoring and inflation systems for a couple of reasons:

Trailers tend to be neglected because they’re often parked at remote yards and terminals where their tires can go flat, causing inconvenient and sometimes expensive delays. And trailers can more easily be fitted with the devices. Unlike truck and tractor axles, trailer axles have interior space in which to run air lines, and hubs can accommodate special valves needed to carry compressed air to tires. So most products now on the market are meant for trailers.

Are they worth the money to install them?

“I would say they are,” says Peggy Fisher, recently retired from the presidency of TireStamp Inc., a high-tech identification system, and who once oversaw the tire maintenance program for the old Roadway Express. “They cost about $700 per trailer, and you can get that back with the (avoided) cost of one flat tire and a roadside service call.”

The systems have become so widely used that members of the Technology & Maintenance Council, in which Fisher has long been active, wrote a recommended practice on them. RP 239 lists three main types:

  • Equalizing system, which ties together the two valves in a set of duals and helps ensure that each tire bears the same amount of weight and turns the same number of revs in a given distance;
  • Tire pressure monitoring system,
    • which watches inflation pressure in
    • each affected tire and warns of abnormal levels, and
  • Tire inflation system, sometimes referred to as “automatic” or ATIS, which monitors inflation pressure and adds air when needed.

Do a web search for “tire pressure monitoring for trucks” and you’ll find at least a half-dozen products that fit into those categories. All have benefits and drawbacks, and all can work on trailers but few can be fitted to power units, including road tractors.

Basically, the closer you are to a rig and more conscientious you are about checking and maintaining tire air pressure, the less complicated a system needs to be. Or you can get by with no system, which a majority of rigs do. If you’d rather not get out with an air gauge to regularly check tires and find an air hose to pump up tires that are low, a TPMS or ATIS would be useful. And it’s more than a convenience.

“If you keep tires properly inflated, you’re looking at 10% more miles before removal,” says Al Cohn, formerly with Goodyear Tire and now a technical consultant and business development manager with Pressure Systems International, which originated the P.S.I. tire inflation system back in the mid-1990s. “Also, you protect the casing by keeping it cool, so it can be retreaded. You improve fuel economy, protect the tire, and add safety. And you’re not stuck on the road waiting for a service call.”

The drawback of any piece of equipment is that it becomes a new maintenance item.

“You can’t just put them on and forget about them,” says Fisher. “They require maintenance, they need to be inspected. … When you service the tires, service the system.”

There are hoses, O-rings and valves with diaphragms that need to be changed. Monitoring and inflation systems can warn drivers via a light on the trailer when something’s amiss, but drivers need to tell the maintenance department about it. Too often they don’t.

“Some fleets have taken the systems off because they found that their tire costs actually went up,” she said.

Another complication: “When a tire is removed, a technician will turn off the system (to keep it from trying to pump air into a tire that’s no longer there) and forget to turn it back on. So drivers need to check that it’s working. Go around with an air gauge to make sure everything is working properly. Even if they don’t own a trailer they should be knowledgeable about the system and tell somebody if it isn’t working,” Fisher said.

Telematics help solve a lack of communications. Systems that began as stand-alone devices have been upgraded so they can be tied into electronic reporting circuits and transponders that send data to fleets’ headquarters, where managers know when there are problems. They also can send routine info. Tire pressure and a host of other functions on trailers and tractors can be observed and sometimes corrected remotely. It’s a new world, and you’re part of it if you want to be. LL