Tony Stewart said Sunday that he wasn’t sure why he was fined $35,000 last week by NASCAR after comments he made about officials not requiring teams to tighten all five lug nuts on each wheel.

NASCAR Chairman Brian France told SiriusXM NASCAR Radio on Monday that Stewart’s fine was based on what he said and how he said it.

“Tony has been very aware of how we approach from a criticism standpoint of the sport and the product of the racing itself and safety is paramount,’’ France told host Dave Moody. “Tony is very aware of how we look at that.’’

After a spate of loose wheels earlier this month, Stewart told reporters last week that “for all the work and everything, all the bulletins and all the new stuff we have to do to superspeedway cars and all these other things they want us to do for safety, we can’t even make sure we put five lug nuts on the wheel.

“It’s not even mandatory anymore. I mean, you don’t have to have but one on there if you don’t want. It’s however many you think you can get away with. So we’re putting the drivers in jeopardy to get track position. … With all the crap we’re going through with all the safety stuff, and for them to sit there and sit on their hands on this one.”

France explained on “SiriusXM Speedway” how Stewart crossed the line.

“I think we have to make judgment calls and how we look at the tone of what someone says, how they’re saying it,’’ France said. “They have ample opportunities, particularly with safety, to deal with us directly on that. But to insinuate that we’re taking the sport down a road that doesn’t care about safety or we’re trying to hurt people, those kind of comments, that goes to the integrity of the sport and we’ll have to deal with that. We go way beyond what any other league would allow in terms of how far people can go in voicing their view.

“There’s just a little line out there that is a bright line and everybody is aware of. Every once in a while we’ll have a driver or somebody else that gets over that line and we’ll just have to deal with it. It’s not a big thing. We deal with it. They understand it and we move on. That’s how it goes.’’

NASCAR announced Monday it was updating its rules on lug nuts immediately.

Follow @dustinlong