baqsed on info given to me by a mechanical engineer ,aluminum based on its physical properties has a limited numbner of cycles before it fails.I have had the tongue of my aluminum trailor crack at the junction of the main crossbrace approximately two thirds down its length .The company had a replacement tongue so I bought it .(the warrenty had run out.)The replacement had more strength in its new design than the original which leads me to assume that they eventually realized that rtheir original design was weak.Today an L shaped bracket which connects the left rear corner of the trallor together broke while traveling a highway speed.Even though the trailor was made by one of the popular aluminum trailor manufacturers my engineer friend suggests that anyony using an aluminum trailor should look for any signs of metal fatigue at high stress points especially if the trailor has a lot of miles on it or has some age to it.JUST A HEADS UP!!!!!