Re: spare wheel?
Having a spare seems pointless, unless you have moved to a single rim size. I run standard size rims, with wider and taller tyers mounted. No way a rear would fit on the front, and mounting a front on the rear would make me very cautious about my driving.
I do have a spare front, and a spare rear in my Toybox in case I need one, as I usually have to wait a week to get the tyers I run in stock.