HAMPTON, Ga. --- Tony Stewart's criticism of the tires used at Las Vegas Motor Speedway in March wasn't forgotten when Goodyear Tire and Rubber Co. picked drivers for a test session last week.

Stewart joined Matt Kenseth, Kasey Kahne and Jeff Burton in a two-day session in what's generally considered NASCAR's vacation time. While everyone agreed the chore was necessary, it proved to be a monotonous exercise of patience and hard work. Each driver spent a day making 10-lap runs, followed by changes to the car and tires and another 10-lap run.

Off-season testing has turned the racing season into a 12-month job. Vacations have gone from months to weeks to days. The wheels never stop turning in an endeavor that already has the longest regular season in professional sports.

Goodyear admitted Stewart was picked for its tire test because of his comments. Not only did he lose a couple of days in the middle of his already-short off-season, but he also had to give up his tickets to the Led Zeppelin concert on Dec. 10 in London.

Goodyear randomly picks teams for its tests.

A year ago Hendrick Motorsports got a significant jump on everyone else with an aggressive off-season testing schedule. The team hired former Busch Series driver David Green to test at non-NASCAR tracks for months as the Nextel Cup Series got ready to implement its Car of Tomorrow. By the time the car hit the track, Hendrick reportedly had logged more than 1,000 testing hours.

Since the new car will be the only car used in 2008, teams are trading in vacations for practice laps. The new car also presents challenges for Goodyear as it tries to sort through a variety of rubber compounds.

Goodyear has as many as 20 different styles of tires, and it has to work through all of the combinations for each racetrack. All that work is done during the off-season and off-days.

"Personally, I don't mind testing that much," said Bobby Labonte during last week's tire test at Atlanta Motor Speedway. "It's not very exciting, but it does give you the chance to work on your car. The best way to learn is to be on the track."

NASCAR limits testing at tracks on the Nextel Cup schedule. The sanctioning body will conduct sessions at Daytona International Speedway, California Speedway, Las Vegas Motor Speedway, Pocono Raceway, Lowe's Motor Speedway and Phoenix International Raceway. Teams are allowed to test at non-NASCAR tracks, but teams aren't allowed to get tires from Goodyear. In fact, tires used at the racetrack have special global positioning system chips to make sure none are taken after a race, forcing teams to buy tires from other companies.

Tire tests are different. Teams not only get to use Goodyear tires, they are part of the selection process.

"There's a lot to learn," Burton said after his test at Las Vegas.

Half the teams who plan to race in the Daytona 500 will test for three days, starting Jan. 7. The other half will test a week later on Jan. 14.

NASCAR also has official tests scheduled later that month at California and Las Vegas.

Kyle Busch, who moved to Joe Gibbs Racing and Toyota for next season, said he will stay busy in January. He not only will be in his Nextel Cup car trying to get used to his new team, he also has plans to do tests for his Nationwide and Craftsman truck teams.

"I've got a tire test in Phoenix in January, along with all the other NASCAR tests," he said. "It's all about getting used to the team. We went to New Smyrna just to get used to the Gibbs stuff on a short track, to get used to the team. We'll go back to Phoenix in January to get used to the Toyota.

"I'll get a few days off here and there in the off-season, but basically we're still at it full-time. Testing's not very glamorous. It's boring. But it's important. If it makes you better once the season starts, it's all worth it."

Reach Don Coble at don.coble@morris.com.