Mine are 255 60 15. Yes everyone will tell you they won't fit. But they do. I had to swap the rear out of mine anyway so I used an 86 Monte Carlo rear. Its 3 inches narrower than the stock rear and the wheels are 15x8 with 3 3/4 inch backspace. They are tight. But the have almost an inch of clearance everywhere and they never rub anything.
Welcome! Where are you stationed in the Country? Lots of great events throughout the U.S., that you'll no doubt want to check out.
No VB and meat pies, but enjoy our BBQ. I spent four years in your country on both coasts. I hope you enjoy your stay in the US and the HAMB.