here is some info from not just wheels in Nottingham - basically if you dont know how your wheels were made or have any doubts dont do it
http://www.notjustwheels.co.uk/index.html Powder Coating or Wet Painting Wheels In short, Powder Coating alloy wheels should not be an option.
In certain wheels, powder coating could be dangerous
For one, unless you know what your wheels are entirely made of you should not expose them to temperatures of up to 400°F as this can alter the strength the wheel affords at the molecular level. Forged aluminium wheels should especially, as these will almost certainly lose much of their strength. Re-crystallisation can begin at around 300°F depending on the make up of the alloy compound.
Powder coated wheels chip easily
Powder Coat is very tough indeed, but this is its greatest downfall when used on alloy wheels or anything else where is is subject to possible stone chips. Powder coat is simply too brittle and chips when subjected to high speed stone chips. This side effect can easily be compared to that of an old army issue enamel mug.
Impossible to repair without a having full refurbishment again
You can’t buy touch up paint to match the colour of your wheels, you’d have to get the closest colour to it which probably wouldn’t be quite right. If you curbed your wheels again after a powder coat refurbishment you are forced only to go to the refurbishers who did them before and hope that they haven’t discontinued your colour. If they went out of business or moved away you’d be guaranteed not to be able to find anyone else to match that colour as these are normally ‘stock colours’.
Limited range of finishes
Most wheel powder coat refurbishers can only offer a range of between 10 and 20 different finishes. Here at Not Just Wheels you can choose from over 40,000 different colours which you can look at on our colour swatches, we’d never expect you to look through all of them so, let us know before you visit us what you’re after and we’ll get a few suggestions ready for you.
Can’t match to manufacturers OEM colours
If you require OEM matching Powder Coat Wheel Refurbishers might apply a coat of base coat and lacquer to match them to your current standard colour, this will certainly be more expensive than their standard prices and just from a cost point of view you might as well have had a professional refurbishment by Not Just Wheels in the first place using the same process the manufacturers have used since alloy wheels became popular.
Lots of Orange Peel
Unlike spraying paint, it is impossible to control the finish of powder coat as it simply sits as it dries in the oven, you will still get a glossy finish but nowhere near as glossy as with paint. We have 2 Devilbiss GTi Pro paint guns, one of them set up specifically for applying the base coat to ensure even cover of the metallic flakes, the other gun is set up to apply the clear coat lacquer in the most even possible manner, massively reducing the orange peel effect.