Inside Racing Service Watanabe: How Iconic Japanese Handmade Wheels Are Crafted

Japan has produced many legendary wheel designs, but few are as sought-after as those crafted by Racing Service Watanabe. The combination of RS Watanabe wheels and a Hakosuka Skyline GT-R is iconic, and their continued handmade production ensures supplies remain scarce. Today, there’s a two-year waiting list for these wheels.

Fortunately, a detailed video now showcases how these legendary wheels are made. Produced by the Japanese Industry Process YouTube channel, the 50-minute documentary reveals every step of the manufacturing process for both aluminum and magnesium wheels. The process begins with melting metal—including recycled scraps—before pouring it into molds. This is done in small, floor-level furnaces surrounded by stacks of molds and tools, far from the massive, high-tech factories Japan is known for.

How Aluminum Wheels Are Cast

The aluminum is heated to 1,292°F (700°C). Workers then scoop the molten metal using buckets coated in graphite for heat resistance. Before pouring, the mold halves and central core—designed as a mirror image of the wheel’s hub and spokes—are heated, dusted with air, and sprayed with a release agent to prevent sticking. The mold halves are clamped together, and the molten aluminum is poured in. The wheels cool under pressure before being removed.

Magnesium Wheels: A Sand Casting Tradition

For magnesium wheels, Watanabe employs an even older method: sand casting. Molds are created from compacted sand, which must be carefully heated and dried to maximize strength and eliminate moisture. Moisture would react violently with magnesium, risking defects. Once prepared, the molds are buried in piles of sand, the metal is poured in, and the sand mold is chipped away to release the wheel.

From Mold to Finished Product: The Final Steps

Even after removal from the mold, the wheels are far from complete. Excess aluminum is removed by hammering or sawing, surfaces are sanded smooth, and any dents are repaired by building up material with a TIG welder before sanding it back to a flawless finish. Some precision finishing is handled by a CNC machine—contrasting sharply with the workshop’s otherwise traditional setup—though stud holes are still drilled by hand using a drill press. Finally, the wheels receive a coat of gray paint before being boxed and shipped.

"It’s fitting that old-school wheels like this are made with an old-school process. And it’s pretty cool to see bits of metal turned into one of the most recognizable aftermarket wheel designs around."

The video provides an unprecedented look into the meticulous craftsmanship behind Racing Service Watanabe’s wheels, a brand synonymous with quality and exclusivity in the automotive world.