Bob's page is good reading....and if I understand things, he's recommending a 205-65-16 tire as the closest size, but also saying that its not available.
However, a check with TireRack shows somewhere in the vicinity of 10 tires in that size( not counting snow tires) 2 of which I would certainly buy becaue of good price/performance ratios (a Yokohama @ $69 and a Goodyear @ $ 89.)
The diameter is right on the money at 26.6" for the Yoko, 26.5 for the Goodyears, fit rims as narrow as 5.5"; section width at 8.2 and tread width 6.6"
Can I conclude that if we could get a 6" wide rim from Dayton and get caliper clearance we could have an elegant (if not inexpensive) solution?
Obviously the tradeoffs are some vintage appearance issues, including non vintage-look wider tires, but gains are in safety including shorter braking distances, improvement in handling and lower replacement cost of tires. Of course, this only solves the problem for those who like wire wheels.
Personally, I would like every potential issue to be raised and the overly optimistics ones shot down as I'm the newbie in the group and saying my mechanical knowledge is limited is still over-rating it.
'74 GTV, '64 2600 Spider