biggest tire that can fit in minitubbed a-body?

thanks for all the replies guys...but its hard now cuz you guys are all over the board with the sizes you run lol....tensec340, are you using stock tubs moved flush with the framerail? and did you move your rearend back at all or trim the front quarters? i always heard that the tallest tire you can run in the stock tubs with the tub flush to the framerail is 28.5, and width is up to measuring....how did the 15x12 fit on that tire, cuz on the M/T site, they only recommend going up to an 11 inch wheel...im assuming you have quite a bit of backspacing in order to be running this combination.

anybody else out there know what the biggest size i can stuff in the stock tubs is, or just want to say what they are running....i was going to go with the MT 325/50R15 on a 15x10 inch wheel (like BrianT) to be safe, but now seeing tensec340 running a 315/60R15, I am wondering if i can go taller in the stock well? Also, how would i determine what backspacing the wheel will need for the tire i am going to run?