Sorry to be a nuisance, Pen, but can you say exactly what you edited please.
In my experience the problem lies with the tyre bitmaps (ie. whbridge0.bmp, etc). The magenta colours on them corresponds to the magenta colour that shows in the game, and by flood filling colse to black (i used 16,16,16) then the tyres lose the magenta in-game. I don't see where ther is any white at all. :s
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