i've used mine and a few mates Maxtrax well over a dozen times now helping extract peoples bogged vehicles on the beach, if you use them correctly you won't damage them, but give it a heap of right peddle and you'll melt the lugs off of them real quick. i've only ever done sand recoveries with them, and IMHO that's where they work best.
the trick is to deflate the tyres more first as usually people are bogged from running the wrong pressures. engage lowrange and slowly accelerate to avoid wheel spin, once the wheels grab you will feel the vehicle lift up and start to move, then once on top of the Maxtrax you accelerate more and away you go. i've seen several sets get the lugs melted on them, each time it was someone not listening to the stop spinning your wheels instructions they were getting and they just kept gunning it.
