Also a 265/60/18 has a diameter of 775.2mm and the OEM 255/55/18 has a diameter of 737.7mm - is this difference too great to use the OEM tyre as my spare?? What about the D3 size of 255/60/18 with a diameter of 763.2mm?
I cannot help with the tyres you are looking for, but it is definitely a no, no to run an odd size tyre anywhere on a constant 4wd drive vehicle. ( or any 4wd for that matter ) Whatever you change to, you will need 5 of.

