Scott,
I first viewed this Spitfire back in March 1980, being allowed to remove the leading edge fillet to hopefully reveal an over-size wing bolt data plate. Sure enough, one was fitted and stamped up with the RAF serial SM914.
I have photographed it on a number of occasions since, the last in 2013. In all the nine locations it has been positioned in the museum it was always supported by two trestle jacks under the firewall...and I have wondered why.
I suspect it was as simple as the tyres and tubes were perished as Tony Saville's current image indicates new tyres have been fitted.

Image :- Peter Arnold November 2013 Bangkok