You mean..
I have this bidon cage on my bike. It's mostly coated in black plastic but the bit in contact with the bottle has worn down to the metal. What effect will it have on my bike's handling, especially down hill and on corners? Should I get my LBS to completely replace it or would recoating be a satisfactory and safe alternative?
No I was meaning more like.
'I have a cut through the rubber and some of the cordage in the sidewall of my tyre such that it bulges by nearly an inch. Also there is a patch or two of cord showing through the tread area. Will it be OK for my planned tour of Belarus or should I buy a new tyre.'
Followed by ten comments that say it'll be fine and three saying scrap it and finally a comment from a skinflint who says,
'Until it's running on the inner tube and a couple of extra patches won't hold I won't consider replacing a tyre, after all my last one cost me £1 10s 6d in 1963.'