I own a 1978 GTE with original wheels, which are narrower on the front than the back. Did once try wider wheels all round but steering shake became impossible, even when balanced and with a new steering damper. OEM tyre recommendation is Pirelli Radial CN 36 185/70 HR 14 front and 195/70 HR 14 rear, however I run 195 Michelins all round without difficulty.
Also refer earlier Forum thread by Vince Petrie Feb 7, 1012.
The stock Puma wheels have very little offset compared to the Beetle wheels. I put 15" X 6" Cosmics on mine with 185-65 tires and had to put wheel spacers (with longer studs) on the back. You can email me and I can send you a picture of how the Puma looks now.