Wow it seems @trigger put me on the spot! I have a build thread on here somewhere about the frame mod i did on my P5. I put 30" Monster Mayhems on mine at the time. They were on a 14" x 7" wheel but i cant remember if they were 3" or 4" back spacing. Im not sure how tall of a tire you can put on before they start rubbing and you should start considering a frame mod or spacers. I went from stock tires and jumped to 30's and immediately did the frame mod. I can tell you they would have definetly rubbed without the frame mod, but i could turn them lock to lock left and right afterwords and they didnt rub at all. Spacers will give you a wider stance and better stability, which is a plus on a P5, but remember the further out you go with spacers or deep dish wheels means that when you turn all the way one way or the other the tire arcs farther back or forward and runs the risk of rubbing anyway. I never put spacers on mine when i had 30's. I wish i could help you better than that. I imagine you could probably just put the 30's on and see if you can live with the amount of rubbing they do. Maybe do some careful measuring after you get them mounted and see if a certain thickness wheel spacer would help out some, or whether you should just jump in and do the frame mod. There are plenty of examples of frame mods on here but you'll have to search for them. Its not a hard mod to do if you have a little welder and a grinder with a cut-off wheel or sawzall. I would show you a couple of links but i have no idea how to do all that fancy computer stuff. Lol I hope this helps you out some. Remember to take pics and share them on here of anything and everything you do to your P5. We all love pics! Lol Good luck