GraviTire 3D HD is a racing game with a slight difference - there's no car, just the tire. The aim of Gravitire 3D HD is to race a tire up and down some of the World's most famous places.
These include Lapland, Miami Beach and The Great Wall of China. Simply touch the screen to get rolling and touch it again when you hit a downhill run to gather speed.
However, that's about it. All of the courses are in a straight line - there are no curves or corners and the physics aren't particularly realistic.