[Roadsters] new roadster tires

[Gary]

My early 1967 SPL311 roadster tires are now 25 years old and need
to be replaced.   I'm thinking about Yokohama H4s but don't know the
appropriate size to put onto my stock wheels.  Or maybe I should get
a new set of mag wheels.   Also, are there any whitewalls available?

I'm still looking for a gas tank sending unit that operates the fuel gauge.

Thanks, Gary