An interesting garden "ornament"

We drove up towards Galway today to look around a house.  The house was rather nice, but it had an "interesting" back garden.  The garden backed on to a huge corrugated iron shed, and a row of leylandii type trees had been planted to hide it - fair enough.  But between the trees and the boundary were these enormous tractor tyres - there were at least 4 piles of two, maybe 5.  

When we asked about plans for these, we were told that trying to get them out would damage the trees, so they were going to be left there.  Amazing.

Afterwards, we stopped at a local hotel for a rather nice lunch, then drove back on scenic minor roads in drizzly rain.