If you went by diameter A 205/70/14 is 25.3" in diameter. A 235/60/14 would be 25.1" in diameter. 225/60/14 would get you closer at 25.5"
Two issues, do these sizes exist and with a 6" wide rim I wouldn't go wider than 225. Rim width and tire width go hand in hand.
Any reason not to get larger rims other than you have the rallies? Personally I think you can't get a better tires with out paying a premium until you get into 17" tires. Then you can have all the modern tire compounds, structure and thread faces you want.
