Seismic Alpha Wheels 75.5mm x 62.5mm 78A set of 4. 62.5mm running surface, Bearing seat offset 6.5%, Square outside edge, straight-cut inside edge. A highly-optimized balance of properties for modern racing. The fastest urethane that the skateboard industry has ever seen, bar none. The largest and most supportive hub ever seen in a wheel this size. Size and momentum to carry you past the competition in straightaways, yet agile enough for quick acceleration, fast edge-to-edge adjustments, and snappy technical pre-drifts. Finely-calibrated width and supremely supported edges for smooth, predictable handling through even the hardest corners.