How does tyre wear work in oval indy car races?

Just had the weirdest race ever. Daytona tri-oval spec Indy online multiplayer. The whole field were on hards. I (and pretty much the entire lobby) had to pit half way through because we’re on severely worn tyres, losing traction on the bankings and some even spun out. Yet there were 2 guys that didn’t put for the whole race and somehow doing 34s laps the whole race and lapped the field by the end of the race. They had no signs of losing traction and they maintained the same lap time pretty much through out the whole race.

How is this possible?