What is the issue that you are trying to fix/change?? Are you have a lot of tire issues that are causing you to use your spare a lot?
I highly recommend an all steel ply tire like the GY G614, Sailun S367, Michelin XPS Rib and Bridgestone Duravis R250 for super reliable trailer use.
I took my new XPS Rib spare tire down for the first time since Feb 2005 recently and replaced it with one of the R250 4 year old R250 that got a 1/4 x 20 SS bolt in the tread. The R250 did not loose air as the bolt was just in the tread. I had been thinking about the brand new 11-12 year old XPS RIB hanging there so long, so it was sent off to tire heaven completely unused. BTW I have a piece of 1/2 all-thread also holding the heavy tire along with the OEM cable winch.
Chris