dual wheel suburban

i found a site that sells a dual wheel kit that will work on my sears for 55 bucks my question is what is the best use for duals. iv heard stories of overstreasing the transaxle. will duals be good for pushing snow. and i currently use ballast filled tires for weight if i fill all 4 tires with fluid that would be a combined weight of about 200 pounds but will the wider foot print increase traction or decrease traction with less compaction. any info from any one who runs duals would be nice