Ok... I have a Readylift 3" SST lift and my offset on my wheels is +18. I have about 1.5 inches of clearance with the wheels at full lock in the front. I still have the factory intrusion bars in the back, but you will gain about and inch if you install the Readylift ones on the backside.
Sorry Paul. I'm running 275/65/r18s on my rig with no problems. I couldn't tell you if yours would work or not. Maybe someone else on here has a better answer for your question.
I went down the CG rabbit hole and bought pretty much everything that I thought I needed to detail a vehicle. I have been very happy with all their products. It was a little pricy, but to me, it was worth it. My truck SHINES when it is detailed!!