Simply put for a Jeeper's perspective:
My Kumho Road Venture SAT KL61s are virtually perfect on the road. To be clear, I'm using a stock size of 225/75r15, not 30x9.5--not sure if that makes a difference, but thought I'd mention it anyway. They generate no road noise that can be heard above all the natural road/wind noise of an XJ (so I'm not sure if they could be heard on a quieter vehicle or not).
My ride improved over my old tires. I don't remember what they were, but they were some low-end Sam's Club ultra-crummy highway tires or something.
My average MPG remains at a healthy 18, and I'm still capable of achieving 20-21 highway when the planets are aligned.
In all road conditions their traction is top-notch. Even in a blizzard, they have been very sure-footed to the point of not losing traction unless I force them to.
I have not tested them off road extensively yet. Gravel, dry dirt path, dry short/long grass: they're great. I doubt they'll handle any significant mud well, but hardly any AT tire does. I have have not driven in any other looser or more rugged/technical terrain/substrates yet.
That's awesome. Thanks for the report. Kumho SAT are good tires. I encourage you to try 235/75R15 or 30 x 9.5 R15 some time in future. They work great on stock XJs, and XJs with up to 2" lift.
On my prior stock XJ (96) I got same gas mileage with 235/75R15 as with stock 225 ATs. 21 mpg highway, or 22 mpg on a good day.
I also used 30x9.5R15 ATs on my 96 XJ. I never tested the gas mileage, but it seemed about the same based on how long a tank would last.
My current (stock so far) XJ (99) has something wrong with it. It got around 14 to 16 mpg on highway with stock 225 ATs, and gets simlar mpg with 30x9.5R15 ATs. Power is weak at mid and high rpm too. I'm trying to track down the engine problem.
235/75R15 gives improvement in off road performance, with no loss in on road performance or gas mileage. I did a lot of wheeling with 235s (old version of Cooper AT). Very good on trails, almost wide enough on sand, but not quite. Great on mild mud, but not quite tall or wide enough for medium mud. i.e. - great on road, great for mild off road, but not quite good enough for intermediate off road.
30x9.5R15 gives a huge improvement in off road performance with loss in on road performance, and only minimal loss in gas mileage. 30s require no mods to use. i.e. - great on road, great for mild off road, and good enough for intermediate off road. I have owned this size in BFG AT, General Grabber AT2, and Cooper AT3. I highly recommend this size. Any loss in gas mileage is minimal. No noticeable loss in power with stock gearing, except for one thing. Reverse is a bit high for backing up VERY steep hills. For this size tire in the mountains, 3.73 diff gears would be ideal, but 3.55 are working fine for me in mountains, except for straining when reversing up VERY steep hills.
I'm glad you're happy with tires you have. I encourage you to try some 235s or 30s in future. Kumho SAT is available in those sizes.