I think it's a combination of them big boots your're runnin' and the Rancho steering dampner. It's an aftermarket piece and I don't put much in the bank on that junk. Are you using the stock rims or an off-set aftermarket rim?

I paid big bucks for RS9000 adjustables, and even the Parts Store Guy was hesitant to sell them. He was right, they didn't do anything whatsoever for my '86 4x4. Within about 2000 miles one started puking out oil, and few thousand miles later another packed it in.

I have to say though the Mother company was Teneco and they were just excellent to deal with. I wrote them one letter, they talked to the parts store and they fully refunded my money. Off they went and I put the stock shocks back on.

Get up close and see if that Rancho is starting to leak. I'd try replacing that dampner with something else first and go for a drive. Next, try to get your hands on a couple of stock rims and tires, mount 'em up and see what happens.