skripo wrote:
When I said max pressure I meant for the trailer tires. The TV max pressure rating is 50.
I still need to find the right pressure combo to soften the ride a bit. I will try 45 rear and 40 front now that I know how to fix the problem.
I find that running the fronts at 50 makes the ride a little harsh.
Hi skripo,
I have been following your post and will see if I can offer some help.
I have found, tire side wall stiffness is a significant factor in establishing a stable towing rig. I had a K2500 Suburban that gave me a heck of a time when when it came to putting new tires on. The same 2500 truck reacted very differently when different brand LT E load range tires were changed. Here is the post if you want to read up more on this.
Stability Effect When Changing Tires - GM 3/4 Ton SuburbanThis is what I had/found.
If the front of the truck has the ability to flex in the tire side wall when the truck and camper are being side wind pushed, the front of the truck will not hold rigid and the "back" of the truck will feel like it just slipped across the road. The jolt is very fast and it knocks you off guard. In my case it was not the semi's bow wave effect but side cross winds.
The end result was this was a tire pressure experiment once I understood what was going on. I had the rear tires at max side wall pressure. (80 psi in my case) The fronts was the adjusting experiment. Leave the back at max side wall cold pressure and adjust the front.
The door sticker said rear at 80 and the fronts to be at 50psi and where I had always towed with for the last 10,000 miles. This was a bad pressure setup for the new brand of LT E's. I found out that there was a global shift better by up'ing the front 10psi to 60. The whole rig became more stable but still not what I had before.
The last experiment, I started out from home (back at 80 front at 75psi) Figuring I can lower the pressure along the way if I needed too easier then pumping it up. Towing down the interstate at 55mph, when I hit a hard bump the front of the truck would jump left or right. With my stiff front end suspension and lack of added truck weight, 75psi was too much. The hard bounce/shifting is not good either. I dropped down 5 psi to 70. 70 was better but still hard in roughness.
I knew 60 psi in my case was the bottom end of where I wanted to go as 50 did not work. I ended up at 65psi as the middle ground. The truck was never as stable as it was before and I have no more pressure left to change. But it was a 90% improvement from the issue when it started. The lessen learned is all LT tires are not created equal when it come to side wall stiffness. And there is no rating for side wall stiffness making it very complex to know which new tires to buy.
I would suggest you leave the rear tires at max side wall. 50 in your case. Only adjust the fronts. If you keep tweaking both at the same time you are not going to figure this out with what you have to work with. The rear of the truck is heavier and it can deal with the added stiffness better then the front can which is lighter (means more bounce on the front)
There will be a point where you cannot optimize the tires any better but it is a knob you can adjust which has to be done anyway in your towing setup.
You mentioned upgrading your tires to LT's. Heads up, that may not be a good or doable option in your case. You stated 20"rims. The
Aspect ratio (defined) on a 20" rim on your truck suggests you have the newer smaller aspect ratio tires. Skinner tires so to speak. Finding an LT tire in that aspect ratio may be complex.
The next part about LT tires is they can be soft side walls at the lower pressures. Worse then you are now. A LT D load range often maxes out at 65psi. A LT E load range is 80 psi. You cannot run them soft as they will not gain you any stiffness. They are made to have air holding the weight. Point: if 50psi is too harsh now, running 60 to 70 psi is going to be worse. Your rims also need to be rated to handle the increased pressure. Going to LT may not work in your case.
As to the rest of your rig,
Yes, the camper tires to be at max side wall pressure.
The comment was made about the truck being level, this might happen but is not a proper sign that WD on the truck is set correctly. If you have scale axle weights hitched and unhitched tells us more then truck being level. Tire fender heights also tell a better story about the WD. If you have auto air suspension that adds a new dynamic to all of this. Need to know if you have this. Just because the truck is level when hitched up does not mean the WD is set correctly. In fact that might be very wrong.
Yes, the camper being level is best but level cannot always be obtained as you can only adjust within 1 hole on the hitch. Next best is slight nose down verses nose up. Do not be nose down more then 1" or else the trailer axle loading can be a long term issue.
Loaded tongue weight per loaded GVW of the camper is critical. If you are in the 13% range, it is OK.
The hitch, I am not convinced your brand of hitch is the best choice for anti sway control in your application. However, also in your case, upgrading the hitch may not solve all your issues. Set the Swaypro up per the instructions for WD and that is the best it can give you. The only anti sway adjustment they declare is add more tongue weight or hitch height. You know you are maxed out now on ability to add more tongue weight. But we or you may not yet know if the WD is setup optimum yet. Since you tow well going down the high way, it suggests your WD may not be real far off, truck stability may be more the issue.
The truck. Your truck can fit many campers but the one you picked maybe not the best combination. I looked up your camper. Nice camper, congrats. The 27', 7" long 10 ft 6" tall and flush slide floor means the camper is high up there catching air currents and long for your truck wheel base and rear overhang (tow ball to rear axle) My son in law has a Durango, just a slightly older one, the prior body design. His has coil rear springs. I'm assuming yours does too. The truck suspension plays a large role in being stable for towing. The stiffer the suspension, the more stable to ward off high profile campers pushing on the truck. There are a few things pushing the limits of your rig dealing with the truck. Soft suspension, softer tires, the truck loaded to capacity with camper weight and passengers trying to deal with a high profile camper verses the truck size. Tire pressure will hopefully get you better. Long term you may need a change in the camper or the truck. In our case years ago, we loved the camper too much and the truck has to change. In my case it was a 2002 Chevy Tahoe that we traded in 2004. Yes a 2 year old truck was traded for the 2003 2500 Suburban.
Good luck and hope this helps
John
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.
