Page 7 says the Reserve has standard 15" aluminium wheels.
Anyway, like a previous poster said, if 15" wheel were such a huge priority for you, it should have been caught at the PDI.
Ah yes, I see that now. I stand corrected.
At least it sounds like there is sufficient clearance for 15" wheels/tires, so that bodes well for the idea that the OP can get these swapped out.
I wish I could fit 15" to my camper, but there is insufficient clearance to do so. Heck, in my case, I'd pay for them myself if they would fit !
My TT was the same way. All the ads, brochures, documentation, stated 15", all the trailers of this model on the lot had 14" The 4 tires are rated to carry 7040lb, more than my 5900lb GVWR, and more than my loaded 5200, so I am not concerned.
2007 Expedition EL 4x4 Tow pkg
1981 Palomino Pony, the PopUp = PUCampin! (Sold)
2006 Pioneer 180CK = (No more PUcampin!)
You said that you wouldn't buy a TT without 15" wheels but you didn't look at the wheels on the TT that you bought? I think you bought that TT with 14" wheels, what does the manufacturer have to do with it?
If RV 15" rims/rubber was on your PDI checklist's "mandatory" items, then I too would have checked it during PDI as well. Once you drive / pull off their lot, it's very hard to go back and ask for upgrades. Upgrades that are listed as "optional inclusions" within their documents.
As plan B, I'd simply use the factory 14" rims "as is" for the next 5-6 years. When its factory rubber needs to replace (which is max 6 years), then replace with 14" rubber, but use next size higher. For example, use 225/70/14" or 225/75/14" instead of factory 205/70/14" (as examples of next size up).