I've had some very positive feedback and a few enquiries about spraying my wheels black. So, I thought i would share the reply I gave to one member on here to save repeating myself and to help other members considering doing the same.
We used wet and dry sandpaper. First 400 grade and then 800 grade. Be gentle but thorough. You need to take the shine off all the original paint, but you don't want to rub right through to the alloy. Keep wetting the paper and the wheel with a clean wet sponge. Before applying the spray paint I very thoroughly wiped/cleaned the surface with a clean rag dipped in metholated spirits to get rid of any grease, wax or silicone that may have been on the wheel. Obvously they need to be towel and sun dried as well.
We only had to use etch primer where the scraped wheel had been repaired with special "metal" filler.
We didn't take the tyres off. Just masked them as close to the wheels as we could by using roughly 6 inch (15 cm) lengths of masking tape to follow the curve of the rim. We masked the whole top face of the tyre. I used nice wide 36 mm masking tape but this doesn't conform to curves very well (hence the short bits used.)
The paint we used was 2 pack Eurethane paint which you add a hardener to. I think it's mixed about 4 parts to one part. Be warned though this stuff is toxic. Fortunately my mate has an air hood to use.
We used satin paint as I think it looks more factory, doesn't show blemishes as much and should make brake dust less obvious. Cost me $55 for the paint and hardener and about another $10 for paper and masking tape.
I got the paint from an automotive paint shop. The sort of place that supplies bodyworks shops.
Half a litre of paint + enough harder to suit that amount was plenty. That allows enough to give the inside of the wheel a light coat as well. My mate did about 3 coats with roughly half an hour between coats and I have a bit left if a need a repair going forward. I brushed the inside of my wheels with some dark grey hammertone paint my mate had left over from a trailer job.
You can buy special wheel paint. Including separate clear coat from places like Autobarn for around $16 a can. I don't know if it would be as good as the two pack though.
If you want to do it yourself, you would need to be fairly experienced and have a fairly sheltered area to work in, but with plenty of ventilation. Because of all the angles of the SR wheels it would be very easy to get runs trying to apply even coats. Allow at least a couple of hours to dry before carefully putting them back on the car. The plastic centre caps do stop the nuts from spoiling the finish. Which is good.
