Looks like a 48spoke rim with a 10mm axle,any bike shop will get you one, again you get a tyre an tube you could be up to €50 or 60 so you might want to look out for a cheap/chucked out bmx with a decent rear wheel an brake if you dont want to get in too deep moneywise!
I picked this up at European Bug In last year and have been restoring it, leaving it in OG paint and patina though as its a 'survivor'!
As I got it..
Polished up!
Currently bleaching the mags!!!
My mate Dan who I bought the Bouncer and the old 67 bug I had, from has recently got addicted to building old school bikes!!
Recently sold this for €450
But if you really want to think about therapy then heres a forum members collection (name with-held as I dunno if he'd want this posted here!)