Stealth wrote: DB9 wrote: That's interesting, in my experience I've always thought the colour was white or light grey. Try doing a google search for tyres-ply or cords exposed and see what colour you think!
Cut in tyre + exposed steel cord + water = rust = brown colour.
Just a thought.
But cord doesn't actually rust, its construction is a little like string if you feel it. steel plies on the other hand maybe.