Ferrari and Mercedes confirmed adjustments to their Formula 1 cars on Thursday after the governing FIA closed a loophole that allowed a lower ride height while avoiding excessive wear of the floor plank.
Cars have a wooden plank in the floor which has to be a mandatory thickness but teams can use metal skid blocks in certain areas to add protection when the bottom of the car hits the ground.
The latest technical directive, issued after this month's Brazilian Grand Prix according to media reports, concerned satellite skids that were allowed without any specified thickness.
Mercedes' Lewis Hamilton and Ferrari's Charles Leclerc were both disqualified from second and fifth respectively for excessive skid block wear in last year's U.S. Grand Prix in Austin.
"We had to make a change but we have also the confirmation before this [from the FIA] that the plank was legal," Ferrari boss Fred Vasseur told reporters after first practice for the Las Vegas Grand Prix.
"I think it was the right attitude for us not to fight because I want to stay focused on the championship and not on this kind of discussion," added the Frenchman, whose team are battling McLaren and Red Bull for the constructors' title.
"But the approach was strange."
Mercedes team boss Toto Wolff said his team had also changed "the way we run the floor".
Alpine principal Oliver Oakes confirmed his team had made "a little change".