A body wheel and tire sizes.

All these sizes are making me crazy. I have a swinger and moved my springs in under the frame. Currently I have a set of 15 x 8 with 4.5 back spacing with a meager225/70 but they are close to the wheel well lip. i roled them to be safe because it was super tight. I would like to run a 275 on there but I would have to really add to the back spacing to get them in there. How are you guys running a 275? Maybe I have a wider brake hub that I am not aware of because the 4.5 BS on that 225 70 I have is already slamming me to the wheel lip. Plenty of room to go back but it would leave me with no front space. suggestions?