► APEX | Why APEX Forged Wheels Have Unpainted Knurled Beads

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Why APEX Forged Wheels Have Unpainted Knurled Beads

Knurling on the barrel of race wheels isn’t new, and it’s becoming a commonly sought-after feature to prevent unwanted tire rotation after a fresh set has been mounted and balanced. The problem with knurling is that it varies in design and effectiveness. Some wheel manufacturers may add knurling to their wheels just to check the box so they can market that feature to customers, regardless of whether or not it accomplishes its intended purpose. Maintaining the effectiveness of our knurling was at the forefront of our minds when developing our line of forged wheels.

During manufacturing, wheels often go through a grinding phase to remove burrs and other small imperfections in preparation for painting. If knurling is added before grinding, then it can lose its sharpness. The less sharp knurling is, the less it can grip a tire’s rubber bead. The depth, width, and pitch of the knurling pattern also has a big impact on how much “tooth” is available to bite into a tire’s bead. Often, the pattern is narrower and shallower than ideal.

Painted wheels typically have multiple layers of paint that can become really thick when combined. A gloss finish can have a base coat, color coat, and a clear coat. Spraying those three layers over knurling can fill in the grooves and round the edges off. The combination of these production compromises can reduce the effectiveness of knurling and cause more tire slippage.

Below is a comparison of the unpainted knurled bead on our forged wheels (left) vs. the knurled bead of a competitor's forged wheel (right).

The first thing you’ll notice about our wheel is that there’s no paint covering our bead. The bead area on our forged wheels is protected from paint to keep the unground teeth sharp. Over time, this surface will oxidize and create a hard, protective layer that’s less slippery than paint. The differences in width, depth, and sharpness are clearly visible and easily felt.

Are you getting what you’re paying for? Not all knurling is equal, so be sure to inspect this feature closely when shopping for wheels.

- Ryan

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