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Watching NASCAR pit crews change tires is one of the activities that most race fans take for granted. After all, they change their own tires after 25,000 miles or so, not after 25 laps, right?

Well, the attention to detail that pit crews pay to the tires on their cars is something that most motorists should pick up on, according to Jerold Shires, the tire specialist for the No. 20 Toyota driven by Tony Stewart for Joe Gibbs Racing.

Shires, who hails from Waiteville, W.Va., shares some of his expertise to help consumers get the most from their personal automobiles.

The most important thing that consumers can do to keep their tires happy is to pay attention to the air pressure, Shires said.

"Passenger tires have an air pressure rating, but most of the time it's a maximum," Shires explained. "That rating is for a full load. For our racing tires, we adjust them to make the car handle."

Shires goes on to say that drivers can do that on their car's tires, as well, for better handling, but that consumers should mainly be concerned about load.

"If it says to inflate to at least 32 pounds, you want to run it a couple of pounds under that so when the pressure builds up, it will be right on the rating. If you run it at full inflation, it will wear out the center of your tire."

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Tire pressure is key to maintaining the contact patch, or the amount of rubber that's actually on the road. Proper tire inflation plays a significant role in fuel mileage, as well, and that's important in the days of $3.50 plus per gallon of gas.

"If you run it low, it's more of a drag on the tire," Shires cautioned. "If you keep it at 30 pounds, say, for a tire that's rated at 32 or 34 pounds maximum load, you'll be better off. The more you keep the tire up off the road, the less drag you have on it and the better your mileage will be."

Improper inflation causes the tires to wear out quicker. You see it on the racetrack, too. Lower inflation means better handling, but it also increases the chances that the tires will be the victim of abuse and fail to perform.

Consumers need to "read their tires" to keep them working well over their useful lives, Shires said.

"The biggest thing to take care of is the air pressure," Shires reiterated. "If you let your tire get too low, you're going to wear out the outside of the tire. If you put too much in it, you'll wear out the center. Watch how your tires are wearing, too. It might be air-pressure-related, but it might also be suspension-related. Keep all four tires at the same pressure, unless you have a sports car where the front and back ratings are different."

By reading the tire -- inside, center and outside -- you can tell if your air pressure is where it needs to be or if you have a suspension or alignment problem.

"If a tire is wearing on the inside, closest to the hub, it's an alignment problem 90 percent of the time," Shires said. "It can also be a tie-rod or other suspension component, which changes the degree of camber and produces tire wear. If it's air pressure, most of the time it's worn on the inside and the outside. If you're at max inflation, it's the center."

Finally, consumers need to watch the depth of the tread on the tires. Goodyear Racing Eagles have, Shires said, about 4/32nds of an inch of tread on them when they're new.

"That doesn't sound like a lot, but it gets the job done," Shires emphasized.

Passenger-car tires come equipped with wear bars all the way across the tire, and learning to read those is useful. If you'd rather do a quick measurement, Shires said all you need is a cent ... a penny that is.

Take the penny and put it in one of the tread grooves, with Abe Lincoln's head facing down.

"If the tread comes up past the head, you're still good; if it's above the head of the penny, definitely get new tires," Shires stressed.