Powder coating versus painting aluminum wheels

I recently purchased a car that came with factory painted red wheels. Not my taste but I wasn’t going to let that stand between me and an otherwise perfect car. The Internet told me I should powder coat the wheels because it results in a more durable finish, but I did some research — and thinking — and arrived at least two potential pitfalls of powder coating.

  1. It’s difficult to get an exact color match with powder coating and consistency in color from wheel-to-wheel can also be difficult to achieve. Something to consider in the wheel color is part of a larger color scheme, as was the case for me.
  2. The process requires that heat be applied to the wheels when applied in order to make the powder flow. This can affect the heat-treatment process used to strengthen the wheel by the manufacture if care is not exercised in conjunction with knowledge of the wheels metallurgical properties and heat treatment process. In other words, by powder coating wheels you run the risk of weakening your wheels.

Still not 100% convinced that painting was the way to go, I called a powder coater in my area who specializes in wheels. I expected them to defend powder coating making thereby making my decision more difficult, but the opposite was true. Below are some quotes from the person I spoke to:

“I’ve heard from different people that powder is not good. I have heard from more people that it is fine. We have powder coated tens of thousands of wheels and have never had any issue with integrity.”

This was hardly a confidence inspiring answer. No engineering and he’s basically saying he doesn’t know.

“Color is the other challenge. Powder silver is usually darker than painted silver. We have tried a number of silvers and have yet to find one that duplicates factory paint.”

My issue with the first comment is that like any structural component, engineers design in safety factor (often a factor of 2x). Thus, I can accept that he has powder coated thousands of wheels with nary an issue. But this is only as observed or reported. If all or most of his customers are unaware that power coating could affect wheel strength (not obvious) then they’d be unlikely to report it in the event of failure. Moreover, the wheel may never fail but if made weaker the customer would never know it.

That none of the local power coaters I contacted were able instill confidence that they had an adequate handle on the engineering consequences of powder coating an aluminum wheel, or at least acknowledge its implications and offer a manufacturer approved process was enough for me to paint. The power coat option simply left too much to chance.

Regarding durability of paint, the shop that did my wheels (Queen City Auto Rebuild, Redmond, WA) claims excellent durability of finish and resistance to chips. Also, my wheels came painted from the factory so if good enough for Porsche, good enough for me. (Ed. note: after over 1 year, paint continues to hold up very well w/ no issues in discoloration or chipping.)

Finally, while not required, I had my wheels stripped down as opposed to having the red painted over. It cost a little extra, but in case of a chip or curbed wheel I didn’t want red showing through. Getting the red paint removed proved to be stubborn so Queen City needed to send them out for a mild bead blast. The stated issues with wheels pitting badly when bead blasted in the past so first attempted chemical only. When that was not sufficient, they sought out a blaster when a more wheel-friendly media so that they didn’t pit. Workmanship was excellent and the wheels looks factory quality.

End result, after having wheels painted silver.

End result, after having wheels painted silver. [Ed. After 4 years, the paint has held up well, even with track use. I’m glad I opted to have the original red paint stripped off as opposed to painted over because there are some chips in areas, which would have resulted in red bleeding through. Instead the aluminum material shows through which only slightly contrasts with the silver paint.]

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