I was loading at my number one shipper and was leaning up against a parked forklift while supervising the loading of my trailer. I will admit that after all these years I had never really thought of what a forklift’s counterweight was actually made from. I knew they had a large 
weight to keep them from tipping forward when lifting thousands of pounds on a pallet, but was surprised by leaning on it to find out that it seemed to be made out of solid concrete. This got me thinking as to how important it actually is for trucks to maintain proper axle weights, not to be confused with legal axle weights!
Maintaining the proper weight balance on your axles is just as important as that very same forklift having a huge concrete counterweight, not just for safety, but for fuel efficiency as well. For explanation purposes, I will use a standard 5-axle setup like mine pictured below, with axle groups labeled 1 through 3. Although it does not cover all of the different setups out there, this will give you a general representation of the principles I am talking about.
No better place to start than in the front with axle group 1. This single steer axle is usually the one with the least fluctuation in relation to load distribution, but is one of the most important. Tire overheating can be caused by overloading the tires past the recommended weight limit, but you also want to be careful not to overload this axle past its weight capacity. If you’ve ever blown a steer tire you know it is not a pleasant experience, but if you haven’t, trust me when I say you want to avoid it at all costs!
Axle group 2, most often referred to as the drive axles, has a lot to do with keeping the equilibrium of the entire truck. Since this group lies in the middle, it resembles the fulcrum point in the whole equation, especially in that of a combination vehicle. If you have to pick an axle most times to be the heaviest, this would be the one that you would want to choose. Watching the same weight capacities as axle group 1 are just as important in regards to axle and tire capacity. Heat becomes a great concern when overloading this set of axles and tires, as they already face immense temperatures from being the turning force between the power-plant and the highway that move you on your merry way from shipper to receiver. The reason you would not want this axle grossly underweight in comparison to group 3 in the rear, is more prevalent in situations when less traction is present. If you have more weight in group 3, it is going to want to push ahead of axle group 2 in a loss of traction situation when braking is taking place. This can often lead to a jackknife, similar to pulling doubles and mistakenly having a loaded rear trailer and an empty front trailer.
Now we come to the most important of the groups in the aspect of fuel efficiency in my opinion, group 3. Being that I have trailer skirts, this axle group becomes that much more important in the saving of fuel. I would be lying if I said I had never hauled a tail heavy, multi-stop load as ”luck of the draw” in the order it was loaded. This scenario can really cause you to be the tortoise on the hill, being passed by the zippy little hare! Not only does lugging a tail-heavy load slow you down and make your engine work harder to climb the grades, it also makes you burn more fuel while doing so! Since the weight is in the very rear, instead of right on top of the drive axles in group 2, it tends to lug the bulk of the load weight and pull it up the hill, rather than carry it, as it would do if all axle weights were proportionate. With skirts, it becomes a fuel-saving game of sorts, to be 
able to run with the axles of group 3 slid as far forward as they can be. This means you can “close the gap” between this axle group and the skirts to enable better fuel economy for that trip. I actually did so for the very trip I loaded while leaning on the forklift, which was only 11 pallets, allowing me to nose-load safely and slide group 3 all the way up to the trailer skirt edge!
Remember that weight limits are not just there to make our lives difficult in loading near the maximum allowed GVWR, they are there for safety as well. A safe and efficient driver will always take into consideration that there are other aspects to equally distributing the weight as well. Remember to think about the pallet count and weight of your load when loading, to help make a better judgment about how to maximize your safety and fuel efficiency by having the proper weights all the way around the truck and/or trailer.