Attention: TDR Forum Junkies 
Hi, all.
I have recently purchased a 1998 2500, 12V, extended cab, 4x4, automatic with ~70K miles which is mostly stock. The tires, however, are 285/75R16s as opposed to the 245/75R16s it came with. Sometimes the back of the truck will getting into a hopping fit, especially on grooved concrete with no towing load. The hopping stops when the pavement changes or if I slow way down. It is not associated with braking. It is not coming from the front of the truck (as I have seen suggested in other postings). I looked at the rear suspension, and it all looks okay to me. (Is there anything in particular I should be looking for?) I am guessing the shocks are the originals, but the sway bar may have been replaced (I can still see a small label in the center of it facing backwards).
Any ideas? This behavior seems to be affected a bit by tire pressure, but given that the tires are not the stock size, I am not sure what the loaded/unloaded pressures should be. I have played with everything from 42-50psi unloaded. With a 3500lb towing load at 55psi the hopping is dampened or eliminated, but I cannot find a combination that works unloaded.
TIA,
--Mike
I have recently purchased a 1998 2500, 12V, extended cab, 4x4, automatic with ~70K miles which is mostly stock. The tires, however, are 285/75R16s as opposed to the 245/75R16s it came with. Sometimes the back of the truck will getting into a hopping fit, especially on grooved concrete with no towing load. The hopping stops when the pavement changes or if I slow way down. It is not associated with braking. It is not coming from the front of the truck (as I have seen suggested in other postings). I looked at the rear suspension, and it all looks okay to me. (Is there anything in particular I should be looking for?) I am guessing the shocks are the originals, but the sway bar may have been replaced (I can still see a small label in the center of it facing backwards).
Any ideas? This behavior seems to be affected a bit by tire pressure, but given that the tires are not the stock size, I am not sure what the loaded/unloaded pressures should be. I have played with everything from 42-50psi unloaded. With a 3500lb towing load at 55psi the hopping is dampened or eliminated, but I cannot find a combination that works unloaded.
TIA,
--Mike
