If you aren't too bothered, then buy a silver touch-up paint from Halfords and keep painting over it to build it up. Finish off with some lacquer, making sure it overlaps the original paint to stop it lifting again. I did this to mine, as you say its good enough for daily use.
I dare say if you took a brave pill, watched some relevant videos on YouTube you could get a much better result by masking the rest of the wheel and tyre, wet-sanding and spraying, blending in the finish then finishing off with spray lacquer.