Does a ball roll faster on grass, tile or carpet?

The fibres in the carpet and the blades of grass (and other particles such as clumps of dirt) may provide resistance, which would likely slow the ball down.

There's also the factor that, unless we're talking about artificial grass, it's also likely that the surface of the grass will be nowhere as even as a tiled surface, which means slopes and inclines could affect the speed of the ball.

Given the above, I'd say it's safe to assume your ball will travel fastest on tile.