Crossword puzzle clue "track races with legs"

"I go on four legs in the morning, on two legs in the afternoon, and on three legs in the evening ..."

Track races with legs

Source of the maxim "Four legs good, two legs bad"

Track for truck races?

Like track-and-field races

___ track (rap track intended to insult)

The inside track, on a track

Vehicles for moving racers from track to track?