John, 15" or 16" rim.
Standard tyres max out just over 26" tall which is a tight fit near the top balljoint (sits above the tyre with the SLALS design). Go outside and have a look.
235/60/15" should just fit (theoretically 26.1" same as 215/60/16 which are a standard fitment)
235/60/16" probably not at 27.1" (theoretically)
Though the Uteman has 235/65/17" (29" tall) on the Mongrel with special offset wheels that move the wheel/tyre more outboard, plus his suspension lift to clear the bodywork.
See it by clicking HERE!
Or at his site www.uteman.com.au
In summary it is the height (diameter) that is the issue not the width as 235's on 7" rim is fine.