Depends if you agree with how the engineers figure load weights. Subtract the 12,000# for the axles and the truck gets the rest. If you expect to see enough axles to hold the GVWR, talk to the engineers. I happen to disagree and believe the axles should be 14,000# minimum.
A larger axle might be better able to withstand the damage that comes from a large pothole or from running over a curb. Maybe. But if you lose camber because of a batch of bad steel, or you burn up a bearing because you don't think the manufacturer's maintenance recommendations are reasonable, a bigger axle won't help.
Engineers select materials that are intended to satisfy the design requirement - and on RVs that means supporting the weight that is actually on the axles, without adding unnecessary weight or cost that would accompany an oversized axle.
So if your trailer has a GVWR of 16,000, you can expect about 20% or 3,200 lbs of that to be pin weight, resting on the truck. The remaining 80%, or 12,800 lbs. rests on the trailer axles. That would mean each axle has to support 6,400 lbs. So on a 16,000 lb trailer, you'll likely see 7,000 lb axles carrying around 6,400 lbs each.
If you don't believe that only 12,800 of the 16,000 lbs is on the axles, try a simple experiment.
Stand on your bathroom scale and see how much you weigh. Then put both hands on a counter and push down. Check your weight while pushing down on the counter. Do you still have the same amount of weight on the scale? Of course not.
Your hands pushing down on the counter are like the pin box pushing down on the truck.
Heartland does offer axle upgrades on many models. So if you're ordering a 16,000 lb trailer that comes with 7,000 lb axles, you can probably upgrade to 8,000 lb axles.
