I've been considering going to 19.5's on my k3500 with SRW. I bumper tow up to 12k for farm bits and bobs. I don't like the squish and sway. Right now I'm running 245/75 16s. I am wanting a taller tire too, but it already sways a bit with the 245s. I am offroad quite (in the fields) a bit as well, which is a negative to the 19.5s since I know they don't flex. I like the 19.5s because Rickson makes a steel wheel that still accepts the factory centers and like the look. (At the least I want to keep a steel wheel). I've never scaled just the rear axle when loaded, but I can't imagine the rear axle taking on more than 3500lbs over curb. It already rides like a log truck so I'm not too concerned about ride comfort. I also like the thought of a tougher tire since I'm just SRW. I don't want to convert to DRW due to clearance issues between fields and reducing tire loading. Thoughts?