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Seismic Alpha Defcon 75.5mm Longboard Wheels

Seismic Alpha Defon 75.5mm Longboard Race Wheel set a new step of performance on traction wheels. Features a 0.5mm concave on the running surface that pre-load the edges for aditional gripness. Fusion 85D firber-reinforced thermoplastic core. Fast, long lasting grip, and slow constance wear. Set of 4 wheels


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75.5mm tall x 62.5mm wide ALPHA Wheels
62.5mm running surface • Bearing seat offset 6% • Square outside edge, straight-cut inside edge
7.8 oz. each • Sold in sets of FOUR wheels
Defcon Formula™: Guinness WR speed • directional slide • long-lasting grip • slow, consistent wear

A giant step forward in race wheel engineering. The Alpha’s stout S-shaped edge profile optimizes lip support, maximizes traction under extreme G’s, and ensures predictable slide initiation and hookup. The running surface features a 0.5mm concave that pre-loads the edges, heightens rebound, and enhances in-slide feedback. The bearing seat is offset 6% for progressive lip engagement and more consistent wear.

The Alpha™ also marks the debut of Seismic’s proprietary Fusion™ core – at 46mm tall x 44mm wide, the largest and most supportive hub ever seen in a wheel this size. Features include a deep “saddle” profile, 8 perpendicular support beams (hollowed-out for lightness and aesthetics), and robust bearing lugs. The Fusion minimizes lateral wheel flex, supercharges edge support, and assures absolute mechanical lock with the urethane. Formed from 85D fiber-reinforced thermoplastic – the toughest hub material in the industry.

Contact Patch
Core Placement
Lip profile
Square Lip
Wheel surface
Defon Formula 76A(Mango); 78A(Mint)
Grip level

Specific References