Disco4 2015: replace spare tire-)
 

Dear all
My spare tire needs to be replaced as it has been repaired several times now.
I have just bought new AT tires .Maxxis AT811 265/50R20
The spare rims is 19" and has the standard continental: 175/80r19 doughnut
I would like to have an AT tires as a spare as well, but will it fit under the car, and what to consider other than added weight and Diesel consumption?
So: A compatible tire 19" would be
255/55/r19 compares diameter 30,4 vs 30" will this be a problem for the differential in the DISCO4?
265/55/19 compares to 30,4 to 30,4", however will it fit underneath the car with the added side width?
or go with the standard 175/80/r19 doughnut spare tire (very difficult to find here) This would however also mismatch the new tires 30 to 30,4

Thank you for your kind assistance
Søren