I'm a bit confused.
I'm assuming your asking about spacers because you're concerned about clearance between the tire and fender?
Spacers wont push the tire out that far, to where the chains wont hit. In fact, since the tires are slightly domed in the middle, they will likely put that dome, center of the tire, just under the lip of the fender, decreasing the clearance.
If you keep the chains tight, as in, let the air out, install the chains tight, use springs or bungies to keep the tight, then air up the tire again, and keep the loose links wire tied down, you shouldn't hit anything. However, I do not know the clearance between your fender and tire on
your tractor, or how thick the chains are.
For that fact, I don't even know if I am answering the right question.