My sticker says 8550lbs GAWR. And the truck rides quite hard at proper tire pressure, interesting. Given that the actual axle is up to the task, would the addition of Timbrens or airbags serve as the equivalent of a spring upgrade?
3500 is the mix pin weight according to the manual, if GVWR of trailer is 16,700, that would put pin weight in the mid 3000lbs range using a 20% estimate. Is there a way to measure pin weight directly? Jayco quotes 2820, which sounds low.
Bags or Timbrens will work for what your trying to accomplish although I wouldn't add anything till your actually hooked up with a road ready trailer .....then decide if the rear suspension needs help.
Actual pin weight on the rear axle can only be measured with the trailer hooked and then a re-weigh un hooked.
I doubt the DRW will have any issues carrying the dry or wet pin weight.
