Alrighty then. The wife and I headed out Saturday on our annual anniversary vacation. We ran the SE across the truck scale on our way out of town, and she came in at 4,050#. Headed down interstate 5 in the right lane at 65 - 70 mph. It's pretty flat, and there were no issues. Jumped off at Eugene, and headed over the Coast Range to the coast. Again, no issues. Got into 3rd a couple of time going up the steeper grades, but we weren't holding up traffic, for sure. Even passed a few slowpokes. Headed down 101 on the coast to the California border, and again no issues.
My take on 31" tires on a stock SE? The combination is good to go, generally, until you get offroad in pretty technical stuff. Even then, grab low range and go for it.