While everyone enjoys a right to pack at his own pleasure, I'm intrigued by: Ride-along spare tires!
Some travelers lash a couple of spare tires onto their bikes, even for less-than-trans-continental rides.
I wonder at the strategy: Are catastrophic failures of the on-the-ground tires expected, likely?
If the service life of the mounted tires is questionable, why not mount the new tires BEFORE departure? Given the total cost of the expedition, forgoing a few miles of wear on the existing tires seems negligible, to me. Loading the bike each day will be easier, without a pair of tire casings in the way, and--a pair of tires fastened high above the rear fender hardly improve handling, or wind-worthiness.
Is fear of tire unavailability along the route a reason for on-board spares? If one is traveling in the continental US, motorcycle shops abound, in most areas. Otherwise, next-day-delivery is generally available at the motel of one's choice. A thoroughly-planned ride might even involve stashing replacement tires at a planned re-supply point along the way. Again, some remaining service life can be sacrificed from old tires for the convenience and security of new ones.
Of, am I missing a FASHION point? Is some cosmetic cachet available from projecting the image of the intrepid traveler with Beverly Hillbillies/Grapes of Wrath spare tires affixed to the vehicle? If so, spare tires could be permanently emplaced on the bike, even for a ride from the house to the coffee shop.
As mentioned, everyone packs to suit himself. I will not project my own requirements and preferences upon others. No, "right," or "correct" procedure exists in packing for a ride. But, unless I'm riding to an area where a replacement tire isn't stocked for a thousand-mile radius, and resupply unavailable for a week or more . . . I plan to avoid redundant tire casings aboard my motorcycle, YMMV!