I actually don't own a centerfire rifle anymore, I sold my last one this spring when I needed to pay bills and that was my .22 Honet. But the biggest caliber rifle in diameter wise was a .45-70, actually I had two of them at one time. The smallest centerfire was that .22 Hornet.
My smallest centerfire rifle is a CZ 527 Varmint in .17 Remington; next would be a CZ 527 Lux in 22 Hornet. Largest bore centerfire rifle is a Marlin 444 lever action. Thanks for an interesting question!