The spare tire is the important part. Almost any tire jockey can mount a larger size spare on the side of the road without to much trouble. Tractor trailers do it all the time.
The spare tire makes it so that on Saturday afternoon in the middle of no where you are not stuck till Monday waiting for a tire store that has your size to open. When the tire is brought to your rig you have absolutely no bargaining power. The price is a take it or leave it price. Get the rig and then buy a new tire somewhere as a spare NOT FROM THE DEALER.
You will save money and frustration