265/75s are virtually the same diameter too (2mm less than 235/85), although wider still at 265mm / 10.43 inches
All three sizes (7.50, 235/85 and 265/75) have been standard on 110's and optional on 90's
Standard size on a 90 is 205 (actually 205/80).
And for what it's worth 205/80 is the same diameter as a 235/70 which is why Land Rover fitted both to Discos
My 90 currently runs 235/70s as it runs Disco alloys but I have a 205/80 spare (less strain on the door hinges, I think of it like a "spacesaver" spare wheel fitted to many modern cars)