15 vs 16 rims on GQ

the outside diameter of a 33 on a 15in same as on a 16in

$500 for a set, thats cheap, they are nearly that a pr from nissan new. but remember if you DO damage one, they are hard to come by, and your up for $380-450 for a new one..

The other issue is 16inch tires arebleeploads more expensive for same size tire. :(

Thats the bonus of Sunnys. $60 to replace.

As Truckster has said, the 15" are cheaper as replacements.
The 31x10.50R15 (OE fitment on some earlier Patrols) and 265/70R16 have got similar Overall Diameters and can be changed without any noticeable difference in power and gearing.
There are some good tyre options in the 16" fitment. Going to a 265/75R16 (same rolling Diameter as the 7.50R16 which come as standard fitment on split rims) opens up the option of tyres with a higher load carrying capacity than their 15" equivalent. This basically equates a better/stronger offroad and touring tyre as they have greater puncture and impact damage resistance and a reduced likelihood of having to replace a tyre from damage.
Price wise they are a little dearer, especially around the 31" Diameter, but then their capabilities have increased also. In a 32", prices are only $20 different and in a 33" just about the same....(depending on brand).
IMO - Go the 16".
Hope this helps,
Ryano

Agree with the other posts. I would add that the range of ply-ratings are greater with 16's. The 15's offer a lot of "floatation" tyres, ie those that are designated 31 or 32 or 33, 10.5x15. Not for load carrying as such but for your occassional use perfectly adequate. Perhaps one point that has not been covered is ride quality. Truckster was correct in stating that a 33 in either 15 or 16 is still 33 overall height, but he did not tell you about sidewall profile.If you have 33 overall height, then the 16 will have a half inch less sidewall profile (1 inch x half), therefore a stiffer sidewall(all things being equal) for the same size tyre. This may be worth considering if you would like a spongy ride characteristic. Which comes in handy for off-road work where you can sponge over rocks and logs and conform the tyre to the terrain for smooth, purposful traction.