Part of that is that 4x4 are heavier in the front than comparable 2x4 and so the 2wd has more weight distribution on the rear than the same 4x4 truck in 2wd .
I am not sure that is the case in this comparison.We have weighed both trucks and there total weight is all but exactly the same.We did not weigh front and back though.The 2WD dually has a bigger motor meaning heavier.It's a moot point in my opinion and the difference if any,would not have made that much more of a difference.Tires maybe,but both were siped by the same tire store..His are 245's mine are 215's but four hitting the road instead of two.
The only reason I responded is there is an "internet" feeling that a 2WD dually is by far in superior to a 2WD single rear wheel setup in the snow or even grass, in this post.
I replied because that is not my "actual experience" using both on the same terrain on the same day or at work going to and from work logging in some nasty weather sometimes.
The op asked about summer tires for his 2WD dually not about winter tires not the pro's and con's of DRW vs SRW in 2WD in the grass(laughing)..My advice is any high mileage tire like the Cooper he pointed out or the Cooper AT-3 that I can vouch for being a good summer tire on a 2WD dually.
I am very interested in what the op finally does because I do not have a closed mind on tire choice for a 2WD dually.