Three Methods. Different Results.
Aftermarket wheels are manufactured using three primary methods: casting, flow-forming (also called rotary forging), and full forging. Each method produces a different internal grain structure — and grain structure determines mechanical performance under load.
For most vehicles, any of these methods can produce a wheel with adequate performance. The Cybertruck is not most vehicles.
Cast Wheels
Casting involves pouring molten aluminum into a mold and allowing it to cool and solidify. It is the lowest-cost manufacturing method and produces acceptable wheels for normal passenger car applications.
The problem with casting is physics: as molten aluminum cools in a mold, it contracts. This contraction is not perfectly uniform, and microscopic voids — called porosity — form throughout the material. These voids are not visible to the naked eye, but they are structural weaknesses.
Under cyclic loading — the kind that happens every rotation of a wheel on a real road — these voids become crack initiation sites. Cast wheels can and do crack under sustained high-stress conditions. On a 6,843-lb Cyberbeast producing 600+ lb-ft of torque, those stress conditions occur at every stop-light launch.
Flow-Formed (Rotary Forged) Wheels
Flow-forming begins with a cast wheel blank, then uses rollers to stretch and compress the barrel section while spinning. This process aligns the grain structure in the barrel, improving strength in that region compared to pure casting.
Flow-formed wheels are a meaningful step up from pure cast. They are lighter (the barrel is thinner due to the grain alignment improvement) and stronger in the barrel section specifically.
However, the spoke area and face of a flow-formed wheel are still cast. The casting porosity that causes crack initiation under cyclic load is still present in the highest-stress areas of the wheel — the spoke roots and hub junction, where failure most commonly occurs under impact loading.
Full Forged Wheels
Full forging begins with a solid billet of aluminum alloy — no voids, no porosity, no random grain structure. A forging press (typically 5,000–15,000 tons of force) compresses the billet into a near-net shape. This compression aligns the grain structure throughout the entire wheel in a continuous, dense matrix.
The result is fundamentally different material properties:
- Higher tensile strength: more force required to stretch the material to failure
- Higher yield strength: more force required to permanently deform the material
- Higher fatigue life: more load cycles before crack initiation begins
- No porosity: no pre-existing failure initiation sites
Full forged wheels are also lighter than equivalent cast designs because the material is stronger per unit weight — the same structural performance can be achieved with less material.
Why This Matters for the Cybertruck Specifically
The Cybertruck combines three factors that make wheel material selection critical:
- Weight: 6,843 lbs generates substantial static and dynamic load on each wheel
- Torque: 600+ lb-ft of instant torque creates torsional stress at the hub junction with every acceleration event
- Steer-by-wire: The absence of mechanical steering compliance means lateral forces are transmitted directly through the wheel with no absorption
These three factors in combination create a loading environment that exposes cast wheel porosity more aggressively than any other production vehicle on the road today. Full forging eliminates the failure mechanism entirely.
This is not a marketing position. It is material science applied to a specific platform. Xolaris wheels exist because we did the analysis and reached this conclusion before designing the first product.