2nd Gen Non-Engine/Transmission Tire Pressure question

[John Berger]

I've been trying to piece together possible causes of my wreck. The one thing that keeps standing out is my shock settings and tire pressure. Towing to Wisconsin I had the Ranchos set to 5 and 5. Tire pressure was 60 front, 50 rear. No handling problems, towing was good. Coming home, I had rotated the tires, the Ranchos were set to 5 and 5, front tires 65, rear tires 60. The trailer was squirrelly all day. Part of the problem was wind, but that seemed to go away after we got into Kentucky. When I was south of Louisville, I stopped and set the front shocks to 3. This seemed to help a bit, but not much. Is it possible I was riding to stiff. I figure my TT probably weighed in at around 8500. I had a couple of hundred pounds of stuff in the bed and it was distributed evenly. Same for gear in the trailer.

 

[mikel]

Hopefully this helps

I have found that on my truck the tire pressure makes a fairly noticeable difference in how the truck handles. Running empty I usually run 45 rear and 50 front as this gives me nice even wear across the tire and a fairly good ride.



The only thing I have pulled that weighs as much as your trailer is a gooseneck lowboy with a tractor and shredder on the back, so I don't know if the behavior of my truck is applicable to your situation. Anyway, I air my tires up to the maximum on the sidewall when pulling because it stiffens up the sidewalls and helps my truck feel more stable. I tried pulling this load with the tires the same as empty and it felt like I was riding on a big cushion or something. The truck didn't feel very well connected to the ground and squirrled around real bad.



I have also driven empty with the tires at full pressure after dropping the trailer off and being too lazy to get out and drop the air pressure. When doing this my truck feels nervous and twitchy. It follows the grooves in the road real bad and rides really rough.



I don't have Ranchos. I'm still running the stock shocks.



Like I said, I'm not sure if my situation is applicable to yours, but I hope this helps.



Later,

Mike



P. S. How was the weight distrubited on the trailer? Most of the tag trailers that I have pulled would sway if the tounge was too light.

 

[WyoJim]

John... Your post indicates that you think the truck might be swaying the trailer because of wrong tire pressure and wrong shock settings.

I believe the truck would have been stable with all of your different settings. Mine is.

Sounds like the trailer was to light on the tongue. Maybe the propane bottles were near empty and the holding tanks were near full. Whatever.



But the real culprit in my estimation is speed. I think every one is towing too dam fast. When a crisis happens, every thing happens in fast time.

5th wheels tow considerably better. But the brake controllers are a short coming. I have to set mine for the highway then reset it in town or it will slide the tires. If I run the in town setting on the highway and have to make a panick stop it won't have enough brakes and will shove the truck. I have to be ready to grab the manual control all the time. Every thing calms down at a little slower speed.

I run 65 without wind and around 60 in the wind. Every body passes me going like bat *****, but by the end of the day we are all camping the same place.

 

[FDziurda]

Shock Settings?

John,



Sorry to hear you had a problem, however, I wouldn't think the tire pressures or shock settings you were using caused the problem. I imagine your rig rode pretty hard with 60 psi in the duals and the shocks set to max.



I have a friend who has a dually with 9000s and he runs his rig at 3-front and 3-rear when towing, however he only runs 50 psi in the rears. His trailer is very similar to the one you tow.



As a rule of thumb, I take the max load capacity of the rear tires and reduce it proportionally to the actual load. Example: Each rear tire might be rated at 2640# at 80psi (total 10,560#). If the rear axle weight was 5,000# then the starting tire pressures would be 5000/10560=0. 47*80psi or roughly 40 psi. At 80psi, the tires can handle 10,560#.



My truck is a 2,500 but this method works quite well. I run 3-fronts & 3-rears with 60psi fronts & 60psi rears, when towing.



Good Luck.



Frank

 

[JGarcia]

John,

I, too, am sorry about your accident. I agree with the previous writers that I don't think it was your shock setting or tire pressure being too high. I tow an 8,500 horse trailer (gooseneck) on my 2500, and I have the 9000's set at 4 on the front, 5 in the rear. My tire pressure is 55 front, 70 rear (per the Dodge tire pressure recommnedations).



Regards, JRG

 

[John Berger]

Interesting point about the tongue weight. Load distribution wasn't a problem, insofar as how we had everything set up on the truck or in the trailer, but the water tanks and propane are pertinent to my situation. I had three tanks on the trailer. I had drained the front grey water tank and the back grey water tank. The front tank was in the very front of the trailer, the black water tank was at the axle and the second grey water tank was behind the axle. The sewer tank was a third to half full. The fresh water bladder was full and it was at the very back of the trailer. The propane tanks were low. That would explain quite a bit. As for the point on going too fast, I agree. I normally run 60-65 and/or as conditions dictate. I was running 70 at times on I-26, but most of that was uphill and in the valleys, so to speak, to get a run for the next hill. Thanks to all for the input. The more I can glean from all of this, means the more I make subsequent trips that much safer.

 

[John Berger]

WyoJim, I think you may be right. My propane tanks were lighter. I also decided to take another look at the picture of my trailer laying on it's side. I had four tanks on the trailer. Three of them were behind the axles, including the black water tank. I was wrong about it riding over the axles. The galley tank was empty. It was rarely ever empty, but was prior to this trip home. Guess where it sits? You got it... right up front, just aft of the A frame. I never towed with it full, but it was usually half full. That's about 100 lbs off of the front of the trailer. That had never even crossed my mind, but it sure does explain the way the trailer towed all day long. Hell of a way to learn a lesson.

 

[WyoJim]

John... This is a good thread. You have done something most people don't do. Analyzed a situation to make a positive out of a negative. The negative will become just a memory, but the experience gained will stay with you forever.



I hope you have many many miles of trouble free towing with your new Montana. I envy your choice.

 

[lizzyhermit]

I tow a 30' TT and the fresh water tank is under the bed at the very back of the trailer. I never tow with it full as I want to reduce the fulcrum affect and the hitch weight is nowhere near the max. The other tanks are at and slightly aft of the axles and I have not noticed any differences if these are full or not.

I heartily second the speed aspect. Just cause I can tow faster doesn't mean I should. 60-65 mph gets me there and in a lot more relaxed mood.

 

[John Berger]

What model?

hey lizzyhermit, what model is the TT you drag around. My TT was a Nomad 2980, with a single slide. It was a 99, also.

 

[lizzyhermit]

model 2690, no slides, just long. the wife just loves to equate our travels to Lucille Ball in Long, Long Trailer.

 

[Fast 1]

John, Sorry about the accident. Glad your all ok.



I agree with the weight distibution. Not enough tongue weight contributed to it. The tire pressures and shock setting just effect the ride being hard or a little softer. Alot of TT do not have the axles back far enough to get enough weight on the tounge, why do they do that? I supposed so people can tow with light vehicles. I remember towing a TT with a full size van and had to put all the junk in the trailer on the front bed so it had enough tongue weight and then it quit swaying.



Verlyn

 

[D6Diesel]

Hey John, very glad to hear everyone is ok. On the 1 ton CTD rams, the front wheels can only hold about 600 lbs more than the front wheel curb weight. The TT might be more stable without the weight distributing hitch. The rear axle can take lots of load. The sway may be less if the tongue weight is allowed to direct it's force right down on the rear axle.