will I need spacers with these?

Hi all.
I am getting a 2010 Polaris 550 eps xp. I will be buying tires for it but do not want to buy spacers. (to save a bit of money) The wheels are the factory 14"
I am looking at swamplites, mega meyhams and zillas in either 27" or 28" sizes
Would I have any problems with any of these?
Also I mostly ride Northern Saskatchewan where it is mostly dry trails and logs but sometimes I need to cross a few pretty snarly mudholes to get where I’m going. Since I do not want to get stuck 15 miles from the next human being I want a tire that really performs well in the mud. (the mudlites on my current machine are not that great). Are the above choices good for this or should I also be considering something else.
Thanks