I have been running the 5 rib on the GQ - 315 / 75 R16 since may 07 and now have just over 40K on them. They are wearing well except for chips and cuts from dirt roads and offroading. Still have about 8-10 mm tread depth - started at 13.4mm - at this rate will easily get 100K plus out of the set.
My only gripe is that they tend to chip a bit if you do some hard offroading on rock country - ripped a 3cm square by 1cm deep chunk out of one lug out wheeling one day... :(
As for onroad manners - excellent and also very quiet... especially after suffering the MT/Rs for 50K.
Recently caned the life out of them on a HARD and fast dirt road rally covering 800km of dirt. I drove the GQ faster and harder than I have ever done before. The tyres performed perfectly and were 100% reliable running at 25psi for the whole event- I could hook along dirt roads at 120 - 130km/h no problems. Tracked straight and were very predictable when they broke traction - which was quite often in the loose stuff
(Came second out of 23... pi55ed off a few of the Commodore and Falcon die-hards
)
I have done quite a few Stockton runs now and they are brilliant on the sand. Air down to 12psi and the truck is damn near unstoppable.
Nowadays I tend to to a lot more touring and on-road commuting in the beast with the odd beach run thrown in. The ATZs really are the most sensible decision I have made on the truck since I threw the turbo on.
They aren't half bad offroad - in the dry that is. Pretty crap in the wet or mud as you would expect but not totally useless. Fine for touring type work in the wet - gravel or tar.
Would I buy them again? I'd have to see what new tyres were on the market at the time and weigh up what I wanted to do with the vehicle first - but yes I would buy them.