356's in the 50's had (I believe) 16" rims - at least my brother's '59 had 16" rims as did his friend's A coupe. I think they went to 15" rims on the "B" series starting in 1960 (but I may be totally wrong about this).
I went with 16" Fuchs on Pearl simply because I could run wider rims (good) with a lower profile (better) and still have a reasonably accurate speedometer (Best) assuming, at the time, that the 356 VDO knock-off speedo expected to see a 16" wheel and 24.5" dia tire, too.
What I found is that, with a speedo that reads kilometers and having to do instant math in my head (never my strong suit), the indicated speed is more of a suggestion than fact but somewhere near +/- 10%, depending on what fudge factor you use.
The other thing I found is that the 16" rim with a 205-245 tire on it fills the wheel well opening very nicely, giving the car a pleasant look, like this:
Beyond that, my days of racing are almost over (although I have a track day coming up at New England's Thompson Speedway's newly restored road course) and all I'm looking for now is a nice all-around tire that doesn't prematurely get dry rot. I'm currently running Michelin something-or-others on Pearl and they ride and handle adequately for me.
As an aside, I had Michelin 275/18's on my late F250 - They were HUGE, cost over $1,300 per set, installed, and had an expected life of 120,000 miles. Fine.
7 years later and after only 21,000 miles (we stopped commuting 1,100 miles to SC and didn't drive it much), they failed the MAS DOT inspection for excessive dry-rot. ?!?!?!?!?!?!?!?
One of those times when "Government intrusion" strikes home........Like when they changed BBQ grill tanks to those new, OPD "safety valves" which only allow 60% of the flow to your grill cookers because a half-dozen Rednecks abused the original design and blew themselves up - ya can't even get a good sear on a steak, anymore