I picked my beetle tires from Coker tire and if I recall, the retail price was pretty cheap to begin with (like stupid cheap- so cheap, I wouldn't consider a used one). Mine are Euro Metric tires, but I'm not sure you can get those any more. I'd call around and see what you can get a new tire for because beetle tires CAN be very cheap.

Balancing them shouldn't be difficult. They usually have trouble with the earlier beetle's wide 5 wheels, but your 72 super wheels shouldn't be a problem unless you have something really funky.

Like Nick said ,  Get new tires unless you want us to read about the wreck. They are out there

i got mine though deprima tire, they were about 67 dollars but not sure if the sell to the public or not

LRB can get them also, just search the general chatter section of the forum for lrb and you will find the thread I started that has his contact info.