60,000km so far on this set of D697LT's. They're probably half-worn, but I rotate them every 10,000km (free because I bought them at Bridgestone). We've done Lawn Hill, Tanami track, Mt Dare, Simpson, Birdsville twice, corner country, Strez etc on them. I drop them to about 28psi on the gravel which seems to work well. Probably 15k of dirt/sand and 45k of bitumen so far. No chipping at all.
Next year I plan to buy a set of Mickey Thompson MTZ's on steelies which I will use for a Cape trip and subsequent bush trips. I'll keep the Bridgestones for commuting to work and they should easily get to 100k. I had the 694LT on my previous vehicle and they still had reasonable tread at 90k, but were starting to feel a bit "hard"