Rubber wedges--old tire?

[Brion Toss]

Hi,
I agree that the tire rubber would be too soft: the main purpose of wedges is to form a couple with the mast step, turning the mast above the partners into a stiffer, cantilevered section. Soft wedges diminish stiffness. One could theoretically damage the mast with wedges, but they would have to be very hard (there is a reason you don't see metal mast wedges) and driven in very firmly. Still, it is a good idea to fill in the entire perimeter, to spread the load, and to have a bit of radius at the tops, to avoid a stress riser there.
Or you could just install Spartite, which I have never known to become loose over time, let alone rattle. Ian, did this happen to you more than once?
Fair leads,
Brion