Mike, your wheels and tyres ARE Mutt items. The Aust 2 Pdr used commercial wheels and normal road tyres, not military NDTs. There were even fitted with hubcaps from a car! You should be able to find some Ford 4in x 16in rims with a 5 on 5 1/2 bolt pattern. The tires are 6.00-16.
Have a look at the
AWM site and look through their collections database, using the search term "anti-tank". You will find plenty of pictures of the 2 Pdr in it's original form.