We get 150-170 inches of snow a year and have 12% grade on the drive. I have a Ford 9N with ag tires and chains and I also have a Kubota B7510 with bar turf tires. I was going to get chains with the Kubota when I bought it but he dealer talked me out of it.
Last winter I never had a bit of problem with the 4wd and turfs (so far so good) but I can't say the same for the 2wd with ag tires and chains. For one thing, it seems like the turfs will ride over heavily packed snow, the ags will start to ride over it, then punch through and leave you hung up.
As for ice. There is no thrill like riding the old 9n down the drive with the tires sliding and the chains not leaving much more than a mar on the ice. Pumping the brakes just seemed to cause more fish tailing than anything else. /forums/images/graemlins/shocked.gif
That was one time I was glad to end up stuck in the snow bank.
The Kubota hardly spun a tire going up or down on the same ice.
There is just no comparison between 4wd and 2wd. If your tractor is 4wd I would definitely suggest you try them first without the chains. If its 2wd, then I would get the chains.
As always, free advice comes with a money back guarantee. /forums/images/graemlins/wink.gif