<VV> EM Spyder - 13 or 14 inch tires

[Steve Brennan]

I am at the stage of my "restoring" my '62 Spyder coupe where new tires are next on the list.  Rather than just replace the 13" rubber currently installed, I wanted to solicit any thoughts on "upgrading" to 14" (or 15") rims/tires.  For whatever reason, the wire wheel hubcaps that came with the car are 14," so that argues for going larger.  Are there other considerations, beyond the limited options available in 13" tires?  In any event, what size tires will work best for maintaining a semi-accurate speedo reading?

Thanks in advance,
Steve Brennan