UPDATE: So i've bought new springs rated for a 3500# axle. The idea of going to a stronger spring sounds good until you think about the fact that if the springs aren't flexing under the weight, something else will. And that'll be the axle. Don't want bent axles, so thought i'd give these another try. Maybe it's been overloaded in the past by a previous owner ? ? ? And maybe i'll never have the problem again. .....time will tell.
So, I had just enough time before heading out with the trailer last friday afternoon to replace 3 of the springs. - Also replaced all of the hardware and nylon bushings. Most of the flat links for the springs to the hangers were badly worn.
New springs got me 3/4" higher. It's not a lot, but so far its enough. I put a strip of masking tape inside the fender liners so i could see if the tires rubbed again and they did not on a 250 mile trip.
I"ll get that 4th spring replaced in a couple days and call it good for now. I was about 500# shy of my max load that i sometimes carry, so again time will tell.
I also stopped at some trucker scales and ran the riggin' thru to see where i was weight wise.
Front axle of truck: 4120#
Rear axle of truck: 4340#
Trailer axles: 6540#
I only had about 2/3 water, and probably 20 gallons in the fuel station.
Truck weighs 7460# according to the scales at the dump - not sure how accurate those are.
So if it's all that simple, there's another 1000# of actual trailer weight that the truck is carrying.