I've got a few sets of tires for my road bike, some of which are the same type of varying ages, others have been used on the turbo trainer, or have a suspected sharp object in them which I could never find.
I'd like a way of marking the tires themselves so that I can keep track of their age and what they've been used for. Just a couple of letters or numbers would probably do.
The question is what pen or paint could I use for this? As most tires are black, a normal permanent marker is no good. It would have to stay on the side wall through winter conditions without damaging the rubber.
Is there anything which would do the job?