Team,

Got a 72 super on lowered struts running a 175/60/15 on a 214 replica rim. Good setup, does rub slightly at full lock but otherwise ok. Getting a set of old school 14 inch Globe rims because they are cheap and handy to me, and I used to have some on another super so bit of nostalgia there. Anyway, all the tyre resize calculators i can find want to go up a size, not down, so i am having trouble finding a size tyre to match up rolling size i have on there at the moment. Globes have 185/75/14 tyres on, obviously no good to me. Anyone able to help??

try this?
http://www.tyresizecalculator.com/ 

says 195/60/R14

Might be a bit "baggy"

Will the offset work on the front of the superbug, I remember see these wheels always outside the edge of the guard.

http://www.willtheyfit.com 

Don't get the Globes, even if they are cheap. The only thing right about them is the 4X130 PCD. They are totally the wrong ET and they will stick out beyond the standard guard.
With the correct ET +50 x6" front and +40 x7"rear (Boxster 16's) as an example will fit inside the standard guards without rubbing and you could run a 205/55 front and 225/50 rear.
Most of the oldskool 4x130PCD wheels are the wrong ET for the car.

175/60r15 = 591mm tyre diameter (175mm x 1.2, add 381mm for 15").

175/70r14 = 600mm diameter (175mm x 1.4, add 355.5mm for 14").

You get the idea.

You can get 175/70/14 or 175/65/14 cheap brand Fullways for as low as $55 a tyre. It is the offset of the rim that makes the difference

the bottom of the ball joint often scrapes on 14 inch wheels on 3 bolt supers

Thanks all, something to think about. Unfortunately Porsche Boxters are pretty thin on the ground in central Queensland, so you have to grab what you can, when you can, and the globes were cheap and accessible. Might have to wind up the front and back a touch to fit them under.

At the end of the day it's your choice.
The biggest problem with air cooled VWs in my opinion is the restrictive 4x130PCD.
The best thing you can do is a Pcd change to popular modern cars eg 5x100 or similar. This opens up a world of cheap factory and aftermarket wheels with the correct ET. Your car will look great with wheels filling the guards, better choice of tyres, better handling etc etc. In my opinion wheels make the car and nothing looks worse than a wheel even smaller than the factory diameter and a high profile tyre (unless on a buggy) but it's your car, your choice.
We only used Globes etc in the old days because we had no other choice.