Masher 2000 are way to big and will really cut down on speed. Too much rotating weight! Could all so put too much stress on your drive train and engine as well. Not good for the dirt around here not sure about where you are but I would not get them.

Cannot find the other ones do you have a link?

For snow I am guessing paddle tires would be good but hard to say, as we only get snow about once every 10 years here then normally not much.

This is what I run and works well on our track. There are other companies that make very similar styles.
http://www2.towerhobbies.com/cgi-bin...?&I=LXJFE1&P=7

Is the surface you are going to run on hard, medium or soft?