There is a lot more to the spare-tire option than just the tire, tire-iron, and jack. You get a different rear wall system to store it.
They used to have the spare tire as standard equipment for every PC until a year or two ago. The longest PCs are quite heavy and I think the factory deleted the tire to reduce the weight on the rear axle. Not just a heavy item, but stored in the worst possible place with consideration to the rear axle's load.
As great as the spare tire compartment is, I think Phoenix could have done a lot better with the spare tire option as of late. I feel they should have redesigned the rear wall with spare tire to a hinged door and made much larger to accommodate large flat items like zero gravity chairs for example. This way they offer one wall system that can accommodate a spare tire or use that space for storage. If you don't get the spare, you have a great place to store other lighter items. If you later change your mind after taking delivery and want a spare tire, you are setup for it. Owners could leave the spare tire home and have the space for chairs when snow-birding, and take the spare along for those more adventurous trips, flexibility for both scenarios.
