Towing question - tire pressure/tongue weight

[John Berger]

I have a Montana fifth wheel. It's dry weight is 9030 pounds. It's tongue weight is 2020 pounds. When figuring the appropriate tire pressure, do I just account for the tongue weight or the trailer weight? I have Rancho 9000's which will be set to 3 and 3. I'll run my front tires at 55 psi. It's the rears that I am interested in.

 

[RustyJC]

John,



You don't give the actual loaded weights, so I'll use the dry weights you gave for illustration - just bear in mind that they're gonna be too low.



The tires of the 5ver are carrying 9030 lbs minus 2020 lbs, or 7010 lbs, and the 5ver's tire pressures should be adjusted to carry at least that much weight.



The rear axle of the truck is going to pick up almost all the 2020 lbs pin weight, so you'll need to add this to the empty rear axle loading of your truck and set the truck's tire pressures accordingly. As far as the tire pressures are concerned, treat it just like you have 2020 lbs of cargo loaded into the truck bed.



You may have good luck with the Rancho 9000's at 3 & 3, but we've found that 4 front/5 rear is optimum for our 13,500 lb GVWR 5ver.



Good luck with the new rig. Hope you and the family have lots of happy, safe miles!



Rusty

 

[John Berger]

Thanks, Rusty. I just need a baseline and dry weight is the best place to start, since that's as light as I'll be. Thanks for the info. There's more math to this towing than I realized. Did I mention that I hate math Since my wreck, math will be good to me :--)



My truck weighs in at 7100 lbs, with everything topped off and the wife and dog as passengers. The trailer wet weight, or GVWR is 12,500 lbs.



Moderator: I put this topic over in the towing forum. I tried to delete it from this forum, but I was told I didn't have admin capability.

 

[BLee]

Seems like my trailer owner's manual says to air up to the max pressure called for on the tire sidewall. On both my truck and trailer, that's 80 psi. Both are load range E. I air up to 80 psi cold, and haven't had a problem yet.



Bill

 

[Steve St.Laurent]

I'll move it over there for you John. BOING Oo.

 

[JGarcia]

John,

I haul a horse trailer that is similar in tongue weight and overall trailer weight. You need to measure the load by tongue weight, which is the weight actually managed by your truck's rear tires. I am using the Michelin E load rated tires and have followed Dodge's instructions, which indicate that max load requires 70 lbs on the rear wheels. At 2000 + tongue weight, you're probably pretty close to GVWR, which I consider to be max load. Some readers' here have a calculation based on load bearing weight to determine the exact air pressure necessary in the tires for any load. I've never used it, I know how much my tongue weight is, and I always keep my pressure at 70 rear, 55 front, with the Ranchos at 4 front and 5 in the rear. All tires have shown minimal, even wear so far at 26,000 miles. Hope this helps.



JRG

 

[JGarcia]

Sorry, John. Just realized you have a 3500, so air pressures may be different. Please excuse the last post!!



JRG

 

[Barry]

EVERY morning that you are on the road with your 5er, check the tire pressure and make sure that it is at MAX cold pressure. Look on the side of the tire and it will tell you what the cold pressure rating is. Keep it there and you will eliminate 90% of tire problems. On my truck, I keep them at 80 psi and rarely rotate them. First set went 65K with almost 50% tread left when I pulled them and sold them to another TDR member.

 

[BLee]

I'm with Barry.

 

[GLASMITHS]

I'm with Barry too

However, I go one step further. Read what I am saying, there is no max air pressure, just load. It is better to be over on the air than under. so I air mine to 90 psi all around on truck and 115psi on 5er (lrG). If you ever run under-inflated you will damage the tire; its not whether it will fail, but when This is for truck rated tires. If you have Cor below, go by max pressure on sidwall. Save your brain for bombing

 

[John Berger]

The scales tell the story

I weighed the rig yesterday. The numbers:



Front - 4020

Rear - 5560

Trailer axle - 8320

Overall weight - 17900. This was with the fuel tank half full and the trailer tanks anywhere from 1/3 to 2/3 full.



My 5ver's dry weight is actually 9420 lbs. All six tires are inflated to 60 psi. The trailer tires were inflated to 82 psi. I dropped them to 70 psi, but I may go back up to 80. The tires were at 55 and 45, with the shocks set to 3 and 4, and the truck floated just a bit, depending upon the road surface. The shocks are still at 3 front, 4 rear. It was a very nice ride home yesterday.

 

[sheldon]

Proper air inflation is the key to carrying weight. You can be too high or too low. Both can cause blowouts by overheating the tires. Contact the manufacturer of your tires. They should have charts of your size with the maximum weight at certain pressures. Some good tire stores might also have them or have the information in a binder or book. Now that you have the axle weights and with the tire charts you should be able to arrive at a proper range of pressure for your tires.

 

[GLASMITHS]

Opinion without facts is like hay eaten by a male cow



This is my last post on this subject... ... ... ... ... ... ... ... ... ... ... ... ... .

 

[John Berger]

Max inflation pressure

FYI - My tires are Michelin 215/85R16 LTX/MS tires. Their load rating is E. The maximum cold inflation pressure is 80 psi. Michelin sets those specs. I have never heard that there is no maximum inflation limit on a tire. I can come to no sane reason to overinflate my tires when I will be towing heavy and on an interstate highway with other vehicles. I've lost one trailer, due to circumstances that were, for the most part beyond my control. I didn't kill anybody else or any member of my family. I also didn't have over or underinflated tires. The tires were inflated to factory specs for the load they carried. I do have direct control over the circumstance under which I tow and with the use of a little bit of math and a good bit of common sense, I should be safe, not only to myself, but to every other vehicle on the highway. I can feel quite secure in knowing that should the unexpected crop up, I'll be as prepared as is humanly possible. When I was on the median of I-26 and my trailer was on it's side, the attending officer was very meticulous on the questions he asked me, not only concerning my condition, but the condition of the trailer and the truck, prior to the wreck. I'm glad I didn't have to tell him that my tires were over or underinflated. He was very very thorough. I found the following corroborating information on my tires from tirerack.com.



Maximum Inflation Pressure



A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. However the tire's maximum inflation pressure should only be used when called for on the vehicle's tire placard or in the vehicle's owners manual. It is also important to remember that the vehicle's recommended tire inflation pressure is always to be measured and set when the tire is "cold". Cold conditions are defined as early in the morning before the day's ambient temperature, sun's radiant heat or the heat generated while driving have caused the tire pressure to temporarily increase.



For the reasons indicated above, It is also normal to experience "hot" tire pressures that are up to 5 to 6 psi above the tire's recommended "cold" pressure during the day if the vehicle is parked in the sun or has been extensively driven. Therefore, if the vehicle's recommended "cold" inflation pressures correspond with the tire's maximum inflation pressure, it will often appear that too much tire pressure is present. However, this extra "hot" tire pressure is temporary and should NOT be bled off to return the tire pressure to within the maximum inflation pressure value branded on the tire. If the "cold" tire pressure was correctly set initially, the temporary "hot" tire pressure will have returned to the tire's maximum inflation pressure when next measured in "cold" conditions.



A tire's "maximum inflation pressure" may be different that the assigned tire pressure used to rate the tire's "maximum load". For example, while a P-metric sized standard load tire's maximum load is rated at 35 psi, many P-metric sized standard load performance and touring tires are designed to contain up to 44 psi (and are branded on their sidewalls accordingly). This additional range of inflation pressure (in this case, between 36 and 44 psi) has been provided to accommodate any unique handling, high speed and/or rolling resistance requirements determined by the tire and vehicle manufacturers. These unique tire pressures will be identified on the vehicle placard in the vehicle's owner's manual.



The tire's maximum inflation pressure is indicated in relatively small-sized print branded near the tire's bead (adjacent to the wheel) indicating the appropriate value. Because tires are global products, their maximum inflation pressure is branded on the tire in kilopascals (kPa) and pounds per square inch (psi). These values can also be found in the industry's tire load & inflation charts.

 

[Bob Cochran]

Will not have time to get to scales with new Keystone Everest before my first tow. I has a GVWR 14,100 # and my tires are the stock Badyear 235 X16 Load range E. Trailer is the same size and load range but made by General.



Can you give me tire pressures to start with for all tires until I get everything weighed? It is a 2001 1 ton dually as my signature and profile says.



I shoiuld know this. :{



Thanks guys.

 

[Casey Balvert]

For the truck, start with the recommendations on the door sticker. For the trailer start at 80 on all four. You are probably close to the GVWR on your trailer.

 

[dewdo]

I have owned two Ram diesels and have had Michelins on both. On the sidewall it says Max cold pressure 80 lbs, That is what I have carried in both the truck and fiver for nearly ten years. No problems except for the bad good years I had on the trailer.



Dewdo in the other Washington

 

[merryman]

What "claimed weight" means??

The hand out flyer for my trailer gives a "dry" weight of 8980 gross and a dry axel weight of 7600 pounds. On the way home with the trailer before we had added anything to it we went over a DOT scale and found that the axel weight was 8400 pounds. The axel weight was within 600 pounds of the claimed total weight, which was in fact 10250

Seems like most numbers comming from manufacturers whether trucks or trailers are 'grabed out of the air' Using those numbers to inflate your tires could lead to under inflation.



Vaughn

 

[Bob Cochran]

Thanks guess I had better up the pressures. I bumped up trailer from I think around 70 when delivered from dealer to 80 cold as it said on the side walls already. I have currently 60 cold in the 4 rear duals and 70 in the 2 front. Will bump all up to 80 as I am sure the badyears call for that on side wall cold max. By the way I am pleasently surprised with the badyears as I have 39000 and they are hanging in there. One of the 6 is just now marginal on tread depth. Will change to Michilens as I have had good results in the past with them.



Nobody has any results with the General trailer tires good or bad?



Thanks merryman, dewdo & CBalvert