Chad Knaus told driver Jimmie Johnson to intentionally damage the back end of his race car if the No. 48 team won Sunday's race at Talladega Superspeedway, the crew chief acknowledged Wednesday.

Knaus admitted giving the five-time NASCAR champion the pre-race instructions in order to "cover our bases" in case 500 miles of bump-drafting knocked the car beyond NASCAR's strict tolerances. Officials likely would have accepted the damage as an excuse if the No. 48 car had not fit NASCAR's templates in post-race inspection.

The conversation between Knaus and Johnson occurred when the crew chief leaned inside the No. 48 car before the race to give Johnson some final words of encouragement. Because Johnson's in-car camera was live on NASCAR.com's RaceBuddy application, the chat was broadcast to anyone watching the feed at the time.

The orders were recorded by a fan (who preferred to remain anonymous for fear of backlash from Johnson supporters) and obtained by SBNation.com.

"If we win this race, you have to crack the back of the car," Knaus could be heard telling Johnson on the recording. "Got it?"

"Really?" Johnson replied, sounding surprised.

"Yes," Knaus said. "Got it? You don't have to have to hit it hard, you don't have to destroy it. But you've gotta do a donut and you've gotta hit the back end, or somebody's gotta hit you in the ass-end or something. OK?"

After Johnson responds with apparent silence (he can't be heard saying anything else), Knaus added, "You'll be alright. Can't take any chances."

When asked Wednesday whether the conversation indicated Knaus was trying something fishy on the back of the car, the crew chief replied, "I don't think that's a fair assessment."

"To be honest with you, here's the deal – racing at Talladega is tough, and I think everybody understands that," Knaus said in a phone interview. "You run 500 miles at 200 miles per hour, and you're bump-drafting and you're beating on one another, and it's real easy for these cars to get outside of tolerance.

"It's a tight tolerance that we're held in. It doesn't take much to be a few thousands (of an inch) off and have NASCAR raise an eyebrow. Just being proactive, I just told Jimmie, 'Look, man – we've just got to make sure there's a tire mark or some type of visible damage.' Just because cars do move when you race them like that."

NASCAR allows a small tolerance beyond the exact measurements specified in the rulebook, and race teams try to use as much as possible without crossing the line.

Officials have warned teams who decide to live dangerously by pushing the limits, and Knaus said restrictor-plate races are stressful for crew chiefs because they can alter the cars more than planned.

"You don't really know how some of that stuff happens from time to time – especially at a place like Daytona or Talladega," he said. "... We all know how sensitive superspeedway racing is to everybody, and when you go into those races, you're nervous about everything.

"From a crew chief's standpoint, there's a lot of things that are said quickly and maybe out of anxiety that don't even mean much."

Knaus said the car was inspected three times prior to the Talladega race – the initial inspection at NASCAR's Research and Development Center, a pre-qualifying inspection and post-qualifying inspection – and passed each time.

In addition, he said it was the same car Johnson used in the spring Talladega race. Johnson won that event, so the car (which was undamaged) was taken back to the NASCAR R&D Center for an extra look.

NASCAR rules are stricter than ever, with severe penalties handed out to those who go too far outside the box – as Michael Waltrip Racing found out on Tuesday after bringing illegal windshields to Talladega.

Knaus has been on the wrong side of the NASCAR law in the past, too. But he said his comments to Johnson were out of concern that a legal car would be bump-drafted beyond the tolerances.

"It's a tight championship Chase," Knaus said. "Everybody's trying to get into it, everybody's trying to do the best they can for their team and their organization. And to try to cover a base, I just threw that out there. We didn't need it anyway, so it doesn't really much matter."