I live in Southern West Virginia. I live real close to the Hatfield and McCoy Trails. I have done quite a bit off roading, on ATV's, UTV's, pickup trucks, jeeps, etc.. Anyways, 4wd is real profitable in these conditions, and differential lock, etc.. I used to do contracting construction, Operated a 4wd John Deere Backhoe.I believe it was the J model. 4wd probably helped with the backhoe, but it has a more evenly ballanced weight between the front, and rear axles. So, the 4wd drive advantage works better on a backhoe than on a lot of tractors. Most tractors, as I understand it, especially the heavy rear, light front end designs, can be improperly ballasted just by the addition of the weight of the 4wd front axle , and front wheels. Taking weight off the rear, as the tractor was designed for. I have noticed that this takes a particular % of the weight off of the rear, transfering it to the front. Given the much larger tire size of the rear, vs the front on most tractors. Front wheel assist, is not 4wd of equal tire sizes like with a truck, or atv. Notice how a pickup truck's rear end can easily spin, even in 4wd, but doesn't obtain much traction, and propel the vehicle forward very efficiently. Backhoes have additional weight added to their front's in a lot of newer Backhoes. Apparently weight was needed to better balance the machine so that it would be more effective in it's 4wd design, with the frontend loader. A lot of standard tractor designs, with light front ends, with light front end axles in 2wd models, I believe were designed to be more efficient in 2wd versions vs 4wd versions, because of the weight transfer towards being over the rear axle. I believe this is why tractors tended to raise up in the front, and would need weights added to prevent this in certain applications. Eventually they incorporated the ROPS. As you might see in a photo of a tractor that has flipped back, because of the design of a tractor, wherein they started putting the ROPs because of tractor rollovers,and that how the weight of the machine rolls front over rear, on the axis of the rear axle, and rear tires. Two large rear ag tires is all I understand is needed, so long as the front of the tractor is light enough, and has just enough weight on it to steer, and not raise up too much. The 2 large rear tires is all the pulling wheel power that is needed to obtain traction, and plow, unless the tractor isn't designed this way. Newer tractors are becoming more, and more like two rear ends, instead of a rear, and a front end. I believe there is a good reason why it is called front wheel assist instead of 4 Wheel Drive..
