Ah ok,
now i understand your problem...
In Germany it is no problem to change the track,
as long as the tires are covered !
remember that for the same track width
the offset 100 mm on a 12 inch rim is about 75 mm offset with a 10 inch
and for the 9 inch rim about 62mm offset
The truck is not my, its one of the rare TGB in Germany.
The Box is from the German Army "Zeppelin FM2"
http://www.zeppelin-systeme.de/fmsheltere.htm
thats my truck last summer, but still a lot of work !
my container is a radio box from the belgian army
Regards Marcus