[MikeK]

Aside from the aforementioned bias construction and increased contact loading due to the relatively narrow profile, there is another factor: Road aggregate abrasiveness. This varies considerably by location. In the USA it is well known that Hawaiian roadways made from blacktop mixtures containing lava and igneous rock grind up tires very fast. Continental US midwest locations that primarily use softer limestone aggregates are much less abrasive.

In all cases cost, materials availability and carefully studied roadway wear (not tire wear) and decomposition analysis determines the road material selected in an area or country. Since you are in New Zealand, you might like to look at this NZ government engineering study: LINK It is obvious durability of the roadway is important, and abrasiveness of the road to tires is not a considered factor.

If your roads contain a lot of sharp igneous rock aggregate your tires will grind up faster than mine do in Chicago, a limestone area.

And then one last factor- do you drive mostly straight flat terrain, or are your tires subjected to curving, hilly paths that surely grind up tires at a faster rate?