I recently bought a new HTT, as my first camping trailer. All in all I was less that happy with the pickup and delivery process. As we did the walkthrough and the mechanic showing us how to use all ...
No doubt, the dealer pirated the spare from another rig on their lot so they could get you signed and out the door... Trouble is, they 'pirated' the wrong size.
Take it back and get the correct size to match the wheels that are on the ground.