It seems that trailer manufacturers are starting to do what automobile manufacturers have been doing for decades. The "car guys" have been using "high pressure mini tires" as a temporary spare for a number of years. It looks like the trailer manufacturers are starting to designate the spare as a temporary, "limp to help only" type of spare. Let's hope they don't continue down that road like the "car guys" and remove the spare completely and replace it with a can of compressed air..... Wouldn't be much help with the way trailer tires tend to "explode" instead of leak.....
As for the wheel rating to 110 PSI, I wouldn't bet on it, but it's probably stamped with "max load" and maybe even "max PSI" on the back side of a spoke. If not, you can get the max PSI from the manufacturer if you can find a part number on the wheel. It'll take a phone call/email to their tech support, but that information is available.
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS