Rubber seals for wing mirrors

[DMC]

Does anyone know if I can buy the rubber seals for the wing mirrors anywhere? I've been looking online and haven't found any at all.
When I say rubber seal, I mean the rubber between the mirror and the wing. Mine have become perished and look unsightly. I want to replace them but can only find them as part of a wing mirror kit.
I assume it's just a rubber washer but I have no idea what size I need. Can anyone help by either telling me what size rubber washer I need or point me in the right direction as to where to find them?

[les]

Some of these rubber washers are profiled rather than being just flat, by that I mean there is a raised rim around the mirror base. However if yours happen to be flat a couple of replacement rubbers are easily made by copying the originals. Rubber from an old inner tube or something might be suitable.

[DMC]

Thanks Les.
I understand about the possibility that the washer could be profiled. I suppose a thin enough rubber washer would do as it would bend with the shape of the wing. I wonder if anyone else has had this problem and solved it?