Air pressure. For trash trucks, there are few words more important regarding the safety and performance of the tires they rely upon.
There's literally thousands of dollars of rubber on each trash truck rolling down the streets of America, ensuring the behemoths make it safely from one stop to the next.
``Air pressure is first on the list. Everything else is second,'' said Rick Fitzpatrick, technical maintenance manager for tires at Waste Management Inc., the country's largest trash hauler.
Getting the most out of these tires all comes down to maintenance and planning, said the fleet manager for Waste Industries USA Inc. of Raleigh, N.C.
Waste Industries has a fleet of about 800 vehicles operating in several states, and the regional trash company takes great pains to keep track of air pressure as a way to extend the life of those tires.
With trash trucks typically shod with 10 or 12 tires, and each tire costing between $345 and $435 each, Fleet Manager David Peck said, a lot more than trash is riding on that rubber.
A tire that's underinflated can cost 20 percent to 25 percent of a tire's life, he said.
So both drivers and maintenance workers at Waste Industries are responsible for checking tire pressure every single day, Mr. Peck said.
Other factors that can influence tire life include the number and location of puncture repairs, whether a truck operates at landfills where there is more potential for severe damage, and the amount of heat that comes off brakes that could cause tire damage.
Trash trucks make hundreds of stops each day and carry heavy loads-two factors that can put great strain on brakes. Heat from those brakes, if not properly managed, can affect a tire's bead and cause failure, Mr. Peck said.
Greg Thibodeaux, director of maintenance for Waste Connections Inc. of Folsom, Calif., agrees that keeping a tire properly inflated is not a lot of hot air.
``Keeping up with the air pressure on a consistent basis so you maximize the life of the tire itself,'' is a key, he said.
Low pressure can help lead to blowouts or ``picking up things'' either at landfills or along the road, he said. A tire that's low on pressure also will cause another properly inflated tire right next to it to shoulder more of the load and wear out prematurely.
Waste Connections performs weekly air pressure checks and also uses double-seal valve caps to make sure dirt stays out of the valve stem, a situation that can cause a tire to develop a slow leak, Mr. Thibodeaux said.
Jerry Milano is a regional maintenance manager for trash company Republic Services Inc., based in Fort Lauderdale, Fla. He rates air pressure and matching tread depth on tandem tires as maybe the two most important maintenance issues.
``When you look at the side of the road and you see those alligators laying out there, the tires that have come apart, typically that's going to be a low pressure issue that causes that,'' Mr. Milano said.
Republic aims to check air pressure in each tire on each of its 5,800 vehicles at least once a week, according to Mr. Milano.
Pulling tires for retreading too early-while they still have tread life remaining-is another important issue, he said.
Mr. Milano described tire maintenance as ``the blocking and tackling'' of a maintenance program. ``It's hot, dirty work.''
But necessary. Companies pay a whole lot of attention to tires because they are a major cost, Mr. Thibodeaux said.
``Tires,'' he said are ``in the top three largest expenses in your truck variables'' along with parts and fuel. ``That's why it's a big focus of ours.''
Mr. Thibodeaux also ``absolutely'' believes that lower air pressure lowers fuel mileage because it creates more of a drag going down the road.