Simon, ATT 117 Special do not have smaller size. The smallest they have is 265/75R15.
As for our Kembara memang tak ada local MT tyre Kalau ada pun imported punya tyre and it will cost a bomb to bring in. So just stick with HT tyre, moreover we are not going to play hardcore.
You can use the tyre that currently I am using, Yokohama AT Geolander. I can say it fairly goodlah. The grip is not as good as MT tapi kalau the road is wet, our MT tyre pun boleh jadi doughnut ma.