I can't see the pictures either, but I would go with tires. They are way cheaper and more versatile. I have seen some incredible mountain snow rigs with tires!
If you're using chrome, search for "Photobucket Embedded Image Fix", been using that ever since they changed everything. It's revived a ton of broken images and build threads.
I've snow wheeled lots of rigs with big tires and single digits air pressure, in heavy snow you can go some crazy places. My utv with tracks would go a lot more places than with the tires on but lost a lot of the sporty feel with all the unsprung weight and decreased turning radius