I have a 2009 Ram 1500 with a dealer installed 4" lift with 35X12.50X20 Goodyear DuraTracs (which are the best tire).

Recently, because the truck seemed to sag in the rear causing other drivers at night to constantly flash their lights at me I installed a 1.5" blocks in the rear under the coil springs. This leveled my truck but now when I haul my quad or pull my trailer above 65 mph the truck begins to uncontrollably sway side to side. It is so bad that on a few occassions the stability control has turned on. I feel it is unsafe to drive when hauling a load.

Does anyone have any ideas what i should look to replace or upgrade? Rear Shocks?, swaybar?, coil springs? and why???

Thanks!

Take a look at the rear track bar and see if the bolts are loose or if the mounting bracket holes are wallowed out.

Went to check the track bar tightness and decided to push against the truck on the back to simulate the side to side sway that I feel when the truck is loaded. I noticed that there was alot of side to side play in the side wall of the tires so I checked the air pressure. The air pressure was at 35 psi and the 35X12.50X20 Goodyear Duratrac tire say to inflate to 65psi cold.

I then remembered that last summer I took the truck to the Silver Lake Sand Dunes and ran the tires at 12psi to run around the dunes and when I aired up to go home I only had filled them to get the light to go off on the dash which was 35psi because I had to pay for the air pumps. I forgot to add air when I got home.

I just aired up the tires to 65psi and the truck seems much more stable. I still need to load the quad in the back and test it out but I'm feeling pretty confident that was the problem. The bigger the tires, the larger the sidewall and the more play side to side you will have if you are low on pressure. Makes sense to me now.

Might have something to do with tire pressure, but that is 65psi max - not the recommended inflation pressure. A 1/2 ton with 65lbs in the tires is going to ride like a lumber wagon.

I am running 45psi in the tires. I was told by a local tire guy to run 35psi in the front and 45psi in the rear if I am going to be hauling heavy loads.

Still need to put the quad in the back and jump on the freeway but I am confident that this was the cause.

Its pretty scary to be driving straight on the freeway at 70mph and have your truck rock side to side so bad that the stability control kicks in and applys the brakes and at the same time kills the engine so you don't lose control and end up on the local news.

I have driven leaf spring suspension trucks for years. While the daily driver ride is better with the coils, I'm not sold on this new rear suspension design. My next truck will be a 2500.

Its hard to compare the suspensions when you have jacked up the suspension on yours. The stock suspension works well for hauling.