Go Fishing for clown tires. After a Toon walks out of Used Clown Cars, they can find the pond within the street.
Recover the tires and return to Used Clown Cars. Talk to Loony Louis.
Defeat six, level three+ Cogs in Toontown Central.
Return to Crack Up Auto Repair, and then go back to Used Clown Cars.
Talk to Loony Louis.