64mm in diameter by 40mm wide. It's a huge wheel and that's the point: at this height, the skateboard rolls over cracks, seams, and gravel that would stop a smaller wheel, and it maintains speed between pushes for much longer.
X-Formula is the urethane Bones developed to handle street skating without getting flat spots. On a wheel of this size, that matters, because a large wheel covers more ground and wears unevenly if the material isn't serious.
99A is the hardness that still slides but grips enough not to betray you on bad ground. It rolls fast and doesn't force you to pick your path.
