These are just a generic rim, you should be able to purchase them locally. however, for a WT Sierra 0 offset probably isn't enough to clear the springs with a 235 85, in any case, locally available. GV rims are 16X6.5's and are 5P and will work work for for a 235 85, but 6.5 is a bit wide for a 7.50 X 16. (also, if it's a consideration, the GV 16" rim can't accommodate a bolted beadlock due to it's construction)
I'd suggest having Gecko make some up at around -10.
No, vitara rims won't work as they're 25P

Gecko, custom manufactured as a beadlock, makeup to suit 255 85 16's. (Jonnoracing might recall the offset, I don't)

GV 16X6.5

Here is a NT running WT axles and 255 85 16's on Vitara rims. Obiovusly as it has underslung springs spring clearance isn't really an issue (although you can see how close they get in this photo) but the reduced track width of the 25P rims was very noticeable.
PS, you don't need 16" rims to have a narrow tyre, although in this case being NHS is a bit of an inconvenience - whilst these are nominally a 10" tyre, they're 7.5" across the tread. Their performance off road is next level.
