Then his crew chief called for gamble on the final pit stop: take two tires, not four.
Busch was all for it and ended up with another win in California.
Heeding crew chief Jason Ratcliff's advice, Busch came out of the pits in the lead after taking two tires on a late stop, then held off Edwards and Harvick to win his third straight Nationwide race at Auto Club Speedway on Saturday.
"I thought four tires was just going to be a consistent call, just give us a third-place run," Busch said after his 46th career Nationwide win, two behind Mark Martin's all-time mark. "But Jason surprised us all and pulled one out of the hat."
Edwards and Harvick had the dominant cars most of the day, leading a combined 112 laps around Fontana's wide 2-mile oval.
Busch figured he had no better than a fourth or fifth-place car, not able to pass the leaders, just good enough to keep them in his sights.
That left it up to the final green-flag pit stop with less than 20 laps left.
Edwards came in first and took four tires. Harvick followed, taking four as well.
Busch stayed out, inheriting the lead, then finally took his turn down pit road with 13 laps left.
Ratcliff initially called for four tires, then changed his mind, which Busch was all for. The quick stop put the No. 18 car about a straightaway ahead of Edwards and Harvick coming off pit road, and had just enough to survive a momentum-killing brush with the wall coming out of Turn 2 on the final lap.
Busch has won five of his past six starts at Auto Club Speedway and three of the five Nationwide races this season after completing the Nationwide-Sprint Cup sweep at Bristol last week. Busch's team, Joe Gibbs Racing, has won seven straight races at Auto Club Speedway -- five by Busch and one each by Tony Stewart and Joey Logano.
"I still can't believe it actually worked out," Ratcliff said. "You think about things like that when you're sitting on the couch and thinking 'oh, if I was that guy, I'd do this.' We weren't going to win taking four tires and I was really surprised to only do the right sides like that."
So was Edwards, at least after his car went up on the jack.
Edwards started on the pole and had a strong car all day, leading 48 laps. He passed Harvick to finish second, but walked away scratching his head after Busch's two-tire gamble worked.
"I didn't think about taking two tires until the left side of the car was going up," Edwards said. "I wondered if someone might just take two."
Harvick finished third and Ricky Stenhouse Jr. was fourth.
Jennifer Jo Cobb had rough day after a dramatic week at Bristol.
The Nationwide series rookie refused to race last week at Bristol because team owner Rick Russell told her he wanted to start then park the car, stirring up a she-said, he-said controversy. Driving for Rick Ware Racing at Fontana, she spun out on Turn 4 after 12 laps, returned a little while later, then went back to the garage. Cobb finished 38th.