Should I Use Sand Or Sinder Blocks To Give Traction During Bad Road Conditions? If So, How Much Weight?

Sand; you can also use it for traction.

Also, cinder blocks may roll or slide around on you.

The amount depends on how bad the conditions are; I'm thinking you've got a 2wd. My brother said he'd shovel about 500 pounds of snow in his full size 2wd and didn't have a problem. You could probably get away with less, maybe 100 lbs over each tire, but trucks are different so a different amount may work best for you.

Around here people usually just keep their snowmobiles in the boxes of their trucks for traction, and so they have a way out if they become stuck somewhere.

I've also seen sandbags, spare tires, things like that.

Snowmobile....that's the best idea I've heard. :D Dual purpose.

I use my sled for the above stated reason. I also keep a couple of sand bags as well. Better idea that won't slide around and they work for putting under the tires.