I had a set of these mounted and have since logged 1,400 miles on them, with about 100 miles on off-highway trails. I am running 20 PSI all around.
The 100 miles of trail were my first experience of this sort.
My Samurai came with a mix of 215/75R15 tires, 3 being A/Ts and 1 being a highway LT tire. All were cracked and dry-rotted, and one lost 10 PSI per day. The spare was in even worse shape. Certainly not what I wanted on my daily commute, much less out in the middle of nowhere...
I went with the stock size because I felt that bigger tires compromised the already low power of the 1300cc Samurai engine. The smaller tires resulted in a 5% improvement in gearing, but the "seat of the pants" feel was more impressive than that. The Samurai just plain felt much peppier with the smaller tires.
On the road, they make a fair amount of noise, about the same as the previous A/Ts, which had a slightly more agressive tread. Hard braking or cornering causes a lot of squeal. The tread feels pretty soft to the touch, much softer than the previous tires, but they seem to have less grip than the older tires did. I feel this is probably due to the one highway tire that was mounted to the driver's side front previously. I feel that the on-road traction is perfectly adequate for the vehicle.
Once on hard-packed dirt, the tires really shine, and grip quite well. They also do well on loose dirt, gravel and small rocks. They did well in shallow mud too.
Two places where they did not do well were both related to snow-drifts. The first snow-drift was an up-hill climb, which I did not intend to cross, but figured I'd nose into it just to see how it felt. I got to the point where the Samurai was fully into the snow, which had mud underneath, and it did not want to go further. I backed out with no problems. I feel that no normal tire, even a dedicated snow or mud tire, would have helped here. The snow was just too deep.
The second snow-drift left a Samurai sized area where ATVs and one vehicle had passed, leaving one tread through the edge of the drift, and the other tire on a slight short slope very close to a sheer drop, that would have rolled anyone sliding over it. I again eased into the drift, this time with one tire on wet dirt, and the other in packed snow. It felt like the Samurai wanted to slide down-hill, so I backed out of it. Here, I feel a mud tire or chains would have been able to handle it. If there had been no down-slope and/or sheer drop-off, I feel the A/T-S would have been sufficient.
Going down and back up steep dirt hills were no problem for the tires. The same for mixed muddy/sandy water crossings.
They do pick up a lot of gravel, which is then ejected when you get up to highway speeds.
So basically, it seems to be a good A/T tire, and left me wishing that the Cooper Discover STT was still available in the stock size. At this point, I figure the Geolandars will be good enough for the trails I plan to ride.
My future plans are for a differential gearing swap and a change to 28" mud terrain tires, but that is for another year. I feel that the stock low-range was good for my intended use of the Samurai on mountain trails and would not want to go to a rock-crawler low-range in order to get better high-range gearing.
This trip did confirm that the stock Samurai is great for my intended use, which is to take mountain trails that I could not take in my other vehicles. It also does suprising well from a road-trip comfort aspect, with only the ride being a bit punishing after 12 hours. At 16 hours of travel, we were both wishing we had stopped for the night, but that would have been true in any vehicle. I plan on putting OME springs on to help with the ride aspect.
INSA, a Spanish company, is looking to distribute tires in the US. They have M/Ts, the Turbo Dakar, Sahara, and Special Truck, that are available in the stock size. Here is hoping they make it over here.