Tony Stewart wants to start rehab from back injury

LAS VEGAS -- Tony Stewart has always marched to the beat of his own drum.

After offseason surgery to repair his broken back, the three-time NASCAR Sprint Cup Series champion was on doctor's orders to avoid sitting or standing.

Stewart followed those orders -- until he couldn't stand the inactivity anymore.

"For a month now, I haven't done anything but just kind of chill out," Stewart said Friday at Las Vegas Motor Speedway before Sunday's Kobalt 400 (3:30 p.m. ET on FOX). "The doctors want me lying in bed and walking. They don't want me sitting and standing.

"I'm definitely breaking the rules. They didn't want me flying out here. They didn't want me in Atlanta (where Stewart attended last week's race). But I can't lay in bed any longer. It's about to kill me.

"We did everything we could. We did everything short of bubble wrap me to ride out here on the plane. We were as comfortable as can be."

Stewart suffered a burst fracture of his L1 vertebra in an all-terrain vehicle accident in southern California's Glamis Dunes in late January. He has X-rays scheduled for next Wednesday in Charlotte, N.C., for the first time since his surgery.

Based on the X-rays, doctors will decide when and if Stewart can begin rehabilitation.

"The biggest thing I'm worried about is just getting this healed properly," Stewart said. "That's my biggest concern, just making sure that it heals right. I'm anxious to get X-rayed next week because I'm very curious about what the progress has been like for the last 30 days.

"We'll wait and see. But it's just a waiting process right now. Honestly, like I said, the biggest concern is just making sure it heals right the first time."

Stewart couldn't predict when he might be back in the No. 14 Stewart-Haas Racing Chevrolet. Until then, he said, Ty Dillon will drive his car in races that feature sponsorship from Bass Pro Shops, and Brian Vickers will be in the car for all other races.

Vickers is driving the No. 14 this weekend at Las Vegas Motor Speedway.

Wider racing groove could mean action-packed Sunday

The combination of NASCAR's 2016 lower-downforce aerodynamic package and the propensity for Las Vegas Motor Speedway to "rubber in" could lead to thrilling racing in Sunday's Kobalt 400, Joe Gibbs Racing driver Carl Edwards said.

"I think the biggest surprise is just how fast the cars are going," Edwards said after his first stint on the track in Thursday morning's test session. "I guess, in my mind, I envisioned the lower-downforce package being slower, but the cars are really fast.

"The second thing that was notable to me, and I think is a real plus, is how the Goodyear rubber is laying down on the racetrack. There's definitely a difference where the cars are running versus where they're not running.

"I think that's going to help the race to be really good, help us have multiple lanes. It's already spread out in the corners. You can already run up to the second groove and make a little time right now. So hopefully that keeps migrating around, and I really hope that stays here all weekend."

On Sunday, Edwards believes the surprisingly high speeds might contribute to some exciting racing.

"The speeds are just high," Edwards said. "There's still a ton of corner speed, a ton of throttle time, so, honestly, I think it's going to be a little treacherous. Just like always, you want the car to be free, and regardless of how fast we're going, there's less air to lean on with the smaller spoiler and all that.

"So I think it's going to be tough. Hopefully, like I said, the groove moves out, and if that's the case, it'll be pretty neat. You'll have guys running the very top, sweeping guys down the back straightaway, catching 'em -- and that'll be cool."

Hamlin hits wall in test

In Thursday's afternoon test session, Daytona 500 winner Denny Hamlin hit the wall and damaged his No. 11 Joe Gibbs Racing Toyota beyond repair.

Enter a backup car, the chassis that was supposed to serve as Hamlin's backup at both Las Vegas and, two weeks hence, at Auto Club Speedway in Fontana, Calif.

In Friday's opening NASCAR Sprint Cup Series practice at Las Vegas Motor Speedway, Hamlin ran seven laps in the backup, posting the 13th-fastest speed (193.778 mph) of the session.

Brad Keselowski topped the speed chart with a lightning-quick lap at 195.327 mph as drivers prepared for the qualifying session later in the day.