Hi Sean
The wheels from a Tamiya FAT could be an answer to your problem.
If You are using a Gun tractor for italeri the wheels should be ok!
By the way. How are you going to make the sparewheel carrier??
I am building danish CMP's and would also like to do a F 60L.
but i do not how the sparewheel carrier works and what it looks like.
I have a couple of pictures from a danish army handbook, I mail them to you i you like
Brian