I have a 69 charger with a 275 40 17 with a 4.5 back space on the front tire . I tried the rear tire on the front its a 295 45 18 with a 5 inch back space it hits the sway bar . what are you guys running? its stock torsion bar and tubular upper and lower arms with Hotchkiss sway bar . I put a 345 30 20 on the rear 12 inch rim with 6 inch back space. But for the front I am thinking 285 40 on a 18 or 19 inch wheel . thinking 4.5 back space still . thanks

Depends how much money you want to spend and how much work you want to put into the car. One trick is to switch to the later style anti-sway bar which goes thru the K frame and hits the LCA in the middle rather than the end. The other option is to use a custom anti-sway bar that has a deeper bend in it to provide more tire clearance.

Here is a picture of a custom anti-sway bar I built to provide more tire clearance. This bar is the early style that attaches to the strut bar and it has a deeper kick in it for tire clearance. Most sway bar vendors leave the sides straight since it saves them a couple of bends. But the straight side rubs the tire sooner. You might find an off the shelf bar with built in clearance or you might need to have one custom built.

What is the intended purpose? with a 345 rear, it will not be likely easy to "balance" that set-up. A 275 is already wider then most go, so that in my book is a plus. If you can figure out a 295 front, you are in rare territory. Anything wider if you can do it, is the holy grail. but worth it IMO. But of course all the rest of the suspension needs to also upgrade if you want to take full account of a nice real tire package.

The Maxim, "everything effects everything else" still applies.