Originally Posted by eubank
Yep, I've been watching this thread, too, and my gut feeling is that too stiff an axle might not be doing the Airstream any favors. When I order ours -- it's going to be a few more weeks -- I figure I'll get as close as possible to the 3200s currently on the rig (for the last 4+ decades), though I also hope that Inland Andy chimes in here to confirm suspicions!
Airstream had a habit of providing axles that gave the trailer a super soft ride.
The problem with that is the payload was limited.
Your original 3200 pound axles can be increased to 3500 pounds, which is under a10 percent increase. That will still provide a soft ride, with some additional payload capacity available.
Generally speaking, torsion axles rated under 3999 pounds, have a tube size of 2 5/8 inches.
When the rating becomes 4000 pounds and up to 5000 pounds, the tube size increases to 3 inches.
Therefore if someone that has an older Airstream that has 3000, 3200, or 3500 pound axles, wishes to kick it up to 4000 pounds, which under some conditions is OK, then the square tube cut out size in the axle mounting plate, must be increased. That is not a major problem, since the alignment of the axle is dependent on the mounting bolt holes only.