"I just got loose going in the corner," said Stewart, co-owner of the team. "Goodyear came down and was worried, but it wasn't a tire problem. Once I got out of the groove, I just ran out of room. I was staying right with it and I just needed another 50 feet to get it gathered up. I just ran out of racetrack.
"The good thing and the comforting part of the situation was that I've got a group of guys that I have the utmost confidence in when we get in a situation like that," he added. "(I know) you'll recover from this and get the backup car out and get it ready and go out and finish the session and finish competitive."
It's the second time in four races that Stewart has crashed and been forced to move to a backup car. At Pocono, he started from the rear of the field after crashing in Saturday practice and won his first race as an owner-driver.
The two-time Cup champion said the worst part of situations like this is the extra work it causes the crew.
"As a driver, you hate to put your guys in that position," he said. "These are long, hard days. ... They're going to have to go through the same procedure that they (went) through first thing this morning. And they're going to have to do that all over again, plus they're going to have to do an engine change before we qualify."
Qualifying was rained out, setting the lineup for Sunday's race by owner points and putting Stewart on the pole, the same thing that happened at Pocono.
But, this time, putting the engine from the primary car into the backup before the rainout was announced, Stewart was not penalized for changing cars or for the engine change.
Stewart said it was important that he got the backup car out for some practice laps.