I am replacing the stock shocks on my truck. I got almost 40,000 miles out of them. I bought Bilstein 5100s and have now read some forms claiming that they will lower my towing and hauling capacity. My truck has the FX4 off-road package coupled with the max-tow. The truck rides pretty stiff compared to other FX4 trucks I have drove, so I would imagine that Ford did something different. Will the 5100s make much of a difference? I do haul a lot of heavy stuff with the truck, but when it is empty, a smoother ride would be nice especially when I go off-road; that is why I went with the Bilstein 5100s. I am no suspension expert, but I was always under the impression that springs determine payload, towing cap, and ride height. Am I wrong?

 

They aren't going to affect your tow rating. Why are you replacing at only 40K miles?

 

They are very noisy, and I'm doing the tires and an alignment, so I figure I might as well do the shocks. Most recommend replacing shocks at 50,000 anyway. I'm going to be putting on a lot more miles also, so I will be there in no time; better to get it out of the way.

 

Shocks have nothing to do with your tow capacity. However, if you get the 5100 and set the fronts to level the truck, you will end up with the rear sagging when towing. Even with a WD hitch. Also make sure the rear shocks are a match to the front. Putting 5100s on the rear would be best as they will have the same return rate as the fronts. You will not get weird rebounds that are different between front and rear.

And yes at 40k, you are due. I usually change the OE shocks out at 30k.