Knurling on race wheels isn’t new, and it’s becoming a commonly sought-after feature.
The problem with knurling is that it varies in design and effectiveness. Some manufacturers may add knurling to their wheels just to check that feature box, regardless of whether it accomplishes its intended purpose.
Maintaining the effectiveness of our knurling was at the forefront of our minds when developing our new line of forged wheels.
Knurling know-how sets us apart
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 our ARC-8R’s knurled bead (left) vs. the knurled bead of a BimmerWorld TA16 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.
Even our painted beads are better
Knurled beads aren’t new to APEX. We’ve been adding them to select wheels in our flow formed line for a while now.
We made sure the teeth on our lower-cost and fully painted wheels were still as sharp as we could get them without resorting to the costlier steps we implemented on our forged line. Our process allows us to maintain relatively sharp knurling despite the paint. You can see the difference below.
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.