No offense but I would have to ask did you have chains on, or what did you hit to stop you after you slid only a foot unless you meant hundreds of feet.
Ag tires are terrible on Ice and hard pack snow in my personal experience and many others. I have trouble climbing a hill in front of my house on hard pack 4wd on and limited slip front axle not even plowing.
Data supports this as well
Friction Coefficients for Ag tires to various surfaces
Assuming your driveway is gravel the coefficient of friction is approximately 0.6
Asphalt and Dry earth are about .75
Hard pack snow = 0.25
Ice =0.1
Tire Friction coeffiecnts
Chains on ice have at least 0.4 based on my research
I have not found a source for Turf or R4's but i hear R4's are also miserable on ICE
Here is a prime example of how much ags suck on ice and this guy probably weights 1.5 - 2 times your rig yes he could have done other things to prevent the crash but i'm sure he panicked. Thus the reason for my question of chains or what did you hit. My R1's perform like this guys. for more proof search you tube some of the video's are pretty funny
Video Link: http://youtu.be/OttvvH8Qzbk