I'm running the 245/70R17 ST Maxx now, and the 235/70R17 AT3. You can feel the weight of the ST Maxx, but MAN have I been surprised by the on-road handling of the ST Maxx. It's been extremely wet here in Colorado, and hitting puddles you can feel the water evacuate while the tire plows through. Controlled acceleration and braking on wet surfaces with both tires, longer braking distance with the ST Maxx (weight). Slightly louder than the AT3, and stiffer E load range vs. the XL load range on the AT3. I'm not running any lift on the WJ Jeep yet, so my control arms are flat which help soften the feel of the E load range tire. The AT3 just left me wanting something more aggressive with the way spring/fall trail conditions are here. Sidewall strength is great on both tires, with nice fat beads so no worries airing down. For me, the ST Maxx solved all the issues ON road that I had with the Trxus MT without compromising the off road traction, durability, and confidence in performance. Hope this helps!
Sam
Just wanted to add, the AT3 was no slouch off road. Tin Cup and Mosquito Pass were run with no issues, and provided a smooth, comfortable ride. Look at the tread depths for all the tires, and I believe the AT3 has deeper tread across all sizes, especially in the LT tire. Coopers also tend to run closer to published sizes.