Presumably permanent 4WD will wear tyres pretty evenly - that's mainly the 'big' landies. The Jap 4WDs (eg Hilux, older Vitara, Terrano etc) are basically RWD, only switching to 4WD when offroad and its 'safe' to lock the axles together. However, most 4WDs (these days) are actually AWD - like Freelander, and older ones will use a viscous coupling while newer ones will use a Haldex. These will presumably all wear the tyres on the axle driven by the VCU/Haldex less than the other.
I don't think Land Rover's "clever" IRD gearing was to address this tyre wear imbalance, rather to try and provide a FWD feel. From Rave...
"...The rear wheels are 0.8% under driven, so in most conditions the vehicle is effectively front wheel drive, with the rear wheels turning the rear propeller shaft slightly faster than the IRD drives the front propeller shaft..."
The 0.8% gearing is roughly the difference between a new (road) tyre and one that needs replacing. If it were to address faster front tyre wear, you'd think they would have chosen a gearing a lot closer to real life differences. However, I did say it was "clever"! I wonder if any other VCU enabled cars had this "clever" gearing difference.