A wheelie is a maneuver that can be done with bicycles and motorcycles; popping a wheelie
gives a bonus, similar to doing a unique stunt jump. This maneuver can be done in Grand Theft Auto: Vice City, Grand Theft Auto: San Andreas, Grand Theft Auto: Liberty City Stories, Grand Theft Auto: Vice City Stories, Grand Theft Auto IV and Grand Theft Auto: Episodes From Liberty City.
To pop a wheelie, press the left dialog stick back. The longer you hold the wheelie, the larger the bonus. It's generally a good idea to get up some speed first, then lift and stop speeding.
In Grand Theft Auto IV, if you can hold a wheelie for at least 500 feet, you get the "Wheelie Rider" achievement.
The motorcycles that you can pop a wheelie with are:
Any bicycle can be used to pop a wheelie, although the best one to use is the BMX.