Youll often see cars run wide if they pick up dirt or dust with slick tires. Youll also often see rubber pebbles lying next to the racing line as seen here. Twitter link. After a race drivers are told to pick up rubber to make the car a tiny bit heavier to avoid being umderweight, which will lead to the tires looking completly gone.
If you want to see what happens with wet tires on a drying track look at "Slicktermediates" wich kinda look like the ones in the OP.
You can totally go 250km/h on the A5 from Frankfurt to Darmstadt, if traffic allows it. That wont always be possible, but typically if it isnt during work traffic, 160-200km/h is doable comfortably, even on other parts of the Autobahn
The longest unrestricted part that ive driven should be the A71, where you can go longer passages without restrictions, save for the tunnels.