Old Akro + 1
baron_beeza, that's a fairly narrow response with a great deal of concentration on rules and rather less on competency IMO.
Whilst it is important to fill in logs and comply with reasonable regulation these are not the arbiter in how well a job is physically done. Nor are all rules and regulations reasonable, or adequately cover certain situations. I'm reminded a little of the old adage 'aviate, navigate, communicate', the corollary in this situation might be 'assess, research, repair, inform' or something similar (probably someone could think of a better way of putting that!).
Given the original query was simply about where to get tyres and tubes from, and no statement that the OP wasn't simply going to hand them to his local AME, I think it's a fairly long bow to draw the way this conversation is going don't you think? I note the OP hasn't bothered to reply...
Incidentaly I seem to recall that in NZ at least a pilot is required to have a LAME sign off on his competency for specific tasks. I would imagine that a competent LAME would ensure an understanding of regs/log requirements etc of the candidate before signing them off as ok on these things....
FP.