Biffle, who last week said he was "90 percent" sure he would sign a contract extension with his current team, Roush Fenway Racing, for 2009 and beyond, cited the fickle nature of the top-35 rule as a key deterrent from considering Childress' fourth car.
"I don't really see that being an alternative for me," Biffle said. "The one thing a guy's got to look at is, I'm third in points [now] and have a chance to make the Chase right now, and I'm running fairly well.
"And to go to a team that has no points and try to qualify for the Daytona 500, and go to Las Vegas and try to qualify, and California, on time, and dodge rainouts -- we see all these teams struggle to get in the top 35. I don't see that as a smart career move for myself."
Per NASCAR rules, teams ranked among the top 35 in NASCAR owner's points are guaranteed a position in the race. Those outside that threshold must qualify via time trials.
"Is Childress a good organization, great cars, great people? Sure. They have that," Biffle said. "You could say the same about Gibbs or any of the other teams. Simply, going from third in points, or whatever you are at end of season, to not being locked in... If you miss two races you have to qualify [into races] the whole season. Engine blows up, didn't make the Daytona 500, and it rains out at California and you didn't get in. That scenario happened this year.
"[If] it happens again you're trying to climb out of a hole the entire season, and if you're a Chase-caliber driver, and you find yourself in a bad situation. Those are things to consider when you're in my situation -- is that something I'd be willing to do, walk that tight rope on?"
Garage scuttlebutt names Bobby Labonte as a lead candidate for the fourth Childress car. His current sponsor at Petty Enterprises, General Mills, will sponsor the No. 33 Chevrolet.
Marty Smith is a contributor to ESPN's NASCAR coverage. He can be reached at ESPNsider@aol.com.