Just took my now 4 year old Kingston in for some work, they found one of the tires was separating, so I told them to put the spare on since it was new and had never left the bottom of the trailer. I was surprised when they called me and said the spare tire was a 15" not the 16" tires that came with the trailer.
When we bought the trailer, the dealer showed me how to raise and lower the spare, but I never thought to check the size to verify it was correct. 4 years later I have a worthless spare tire and rim.