Trailer Tire Pressure

[DogDiesel]

We shall have to Agree to DisAgree

I read and keep up with the over-the-road trucking industry, who runs max air pressure, and cite not running max air pressure as a significant detriment to reduced mileage and reduced tire life. If I address this topic from an automobile mindset, we agree about handling, harsh ride, bounce, wear pattern, but when approached as a topic about hauling loads, and safety, I will not change. I will run max pressure the tire warrants. Period.

I have 5 trailers, GN RV, GN equipment hauler, BP equipment hauler, GN enclosed trailer and GN horse trailer.



I can tell when air pressures are low without a gage. It feels like I am pulling a sled. Air up and pull EZ. Also, my GN enclosed trailer has bias ply tires, and it pulls like a loaded lead sled. As an experiment, I pulled the rims/tires off my RV and put on it, and it pulls like half the weight is back there. When the bias tires are dry cracked more, I will replace them with radials. No brainer. ($$$)



In an earlier posting, I said I check tires for warm sidewalls. Take the load up to speed, run for an hour or so and coast to a stop. I have found slipped radials (GY) that were replaced via warranty this method on my RV.



These postings can go on, and I really do not concern myself with what any tire manufacturer posts on the internet (they want to sell tires). My trailers will continue to have max allowable air. I buy the tires, and I fix the problems caused by bad maintenance. I have changed a few tires with a loaded trailer, only to have a jack bury into asphalt. Its easier to never change a tire. I have sliced back brake wires when tires peel tread off. On max inflated tires, never a problem with tires ran at max pressure.



If I had unlimited funds and someone else did my maintenance, I might have a different opinion. I am humbly not wealthy, and unfortunately have moved many times in the last 30 years and travel extensively. I know what works, I know maintenance, I know enough about tire theory not to get into the adjustable tire pressure on trailer discussion. If I can have LR E tires on a trailer, it will run them. I know radials are better than bias.

I can agree to disagee.

Thanks



Wayne

 

[klenger]

Brakesmart installed and working fine for over 2 years. I'd buy another one, even at the higher price.

 

[Loren]

It's true that higher tire pressure will result in a smaller contact patch, but that will not result in lower traction. Friction is a function of the coefficient of friction, which depends on the two surfaces, and the weight on the tire.



This is why our trucks have rear-wheel ABS. There is very little weight on the rear axle to begin with, and when you stop suddenly, much of that weight is transferred to the front axle. With the reduced weight on the rear axle, the tires will lose traction and slide.



There are several advantages to running slightly over-inflated rather than slightly under-inflated, but it was best said earlier by Foil Freak 1211. I've heard of lots of tire failures from under-inflation, but I've NEVER heard of a tire failure from over-inflation.



Another advantage to higher pressure is better performance on wet pavement. Hydroplaning speed is a function of the contact patch's aspect ratio (length vs. width) and the tire pressure. A long, narrow contact patch will hydroplane at a higher speed. A higher tire pressure will hydroplane at a higher speed. Both of these are desireable characteristics on wet pavement.



Higher inflation pressure will result in less sidewall flex. This will generate less tire-destroying heat. It will also mean that the tires will wander from side-to-side less than with a lower pressure. This sounds to me like improved handling with higher pressure, although if you are concerned about the slight differences in handling that you will get with different tire pressures on your trailer, you are probably driving way too fast.



If you really know what you are doing, you can get away with consulting the tire pressure charts and running less than maximum pressure. Most of us, however, will be well served by running at the maximum allowed by either the tire or wheel limit.



New subject: I also have been running a BrakeSmart since October 2004. I have accumulated about 7000 towing miles since then. If anything ever happens to my BrakeSmart, I'll buy another one no matter what the cost.



Loren

 

[J&LRam]

when I pulled trailers, a 28'/32'38', flatbeds loaded with construction materials to our next job sites we learned the hard way about not using max , 80 psi in 16" load range "E" tires, as we spent to much down time with tire problems. All my trailers have max tire pressure for several reasons. They run cooler/less chance of tires internal belt slippin' or breakin' when making hard turns/less chance of sidewall damage do to road hazards/tow vehicle gets better fuel milage. On return runs with empty trailers we never wore the centers or had traction problems. We have one old Goodyear truck tire dealer thats been in the business for 35 + years says to use max pressure in any heavy trailer tire, 16" "E" and bigger. Talk to some hotshot/contract folks using trailers with 16" "E" tires and they will tell you to forget about tire charts and use the max.

Just remember the Ford Explorer/Firestone tire and runnin' underinflated tires.



JIM

 

[BILLUA]

When I tow anything, on a trailer, I always inflate the tires to max psi listed on the sidewall when the tire is cold... Do I want to run the tire right at it's limit via lowering the air pressure, or do I want extra capacity and not as much stress on the tire by running the tire with more air (up to max) allowing for more weight to be carried per tire? Seems like a no brainer to me.



Cheers, Bill

 

[KWheaton]

Didn't anyone think about what a tandem / triple axle trailers suspension does when it's running down the road? Every pothole transfers up to the full weight of one side of the trailer to the other axle(s).



My tires are full pressure all the time.



Kevin

 

[PatrickCampbell]

Great point, I run 80 PSI. I know that on my triple axle sometimes only 2 axles are touching the ground. Usually this happens either for a very brief second or when going 5 mph going over some uneven ground.

 

[GWBourne]

i run all of mine at max ALL the time. truck and trailer, loaded and unloaded.

Why? because it lets the tread on the tires run properly and it helps with MPG. less rolling resistance.

 

[Cattletrkr]

On my trailer I run max air (125psi) because the load requires it, but on the truck the max is WAY too much.



The Mich XDE 16ply 19. 5's are rated for 125psi, I run about 75. They do squat a little when fully loaded, but less than a 10ply (stock size) at max air. They wear beautifully. If you follow the pressure chart, you shouldn't have a problem. If the tire companies were trying to sell more tires, they'd tell you to overinflate, thereby wearing the tires out sooner.



If you don't like the thought of running lower pressure, air them up. You won't be hurting anything other than you back (bounce bounce bounce). Just as long as you know that's why you'll be replacing tires prematurely.

 

[War Nerve]

I agree with MAX pressure on the wagon. My 8. 25R-15 are rated for 6k at 120 psi and are load range J. Yeah, that's right J! They stay maxed out regardless if the trailer is empty or has 12k on the deck. I played the lower air pressure game once and lost. Believe me it's no fun changing a seized on 100lb. wheel/tire combo along side I-78 at 9:00 at night with 16k resting on a bottle jack. Fill'em up.



Chuck

 

[Bob Cochran]

To add fodder to this posting. I sent the following email to General tire concerning problems I had with their tire on this trip. Bottom line I am not happy with the General tire model in this application.



This more for your information and knowledge concerning the Grabber AW tires provided on my 35 foot Keystone Everest 5th wheel trailer when purchase new. The tires are 235 85R 16 loade range E were less than 4 years old and upon close inspection had NO signes of UV damage such as sidewall cracks, etc. Nor any inidcation of physical damage to the tires prior to this trip. Traveling this summer I had made it through Utah into Idaho from my home base in eastern Arizona. I checked tires each travel day for physical damage and correct air pressure as I had on this day each tire aire to 85 psi as indicated by the weight of the trailer which has been weighed on certified scales at a Flying J and tires not over loaded. 30 miles East of Boise Idaho before I could get stopped I had a significant blow out on the left rear axle tire with only the inside and outside sidewall remaining. Tire was removed and spare installed and new replacement spare purchased in Bosie.



Now after traveling through the rest of Idaho, Washington, Oregon, Northern and Southern Californa back into Arizona I found another problem this time on the right front axle where I was missing at least 2 feet of tread from the tire. Again before leaving that morning all tires aired to 85 psi no physical indication of physical damage. After leaving Bullhead City Az. I stopped in Williams Az. and tires seemed fine. Decided to stop in Flagstaff Az. and found the tread missing and the tire removed and replace with the spare.



Also speeds never exceed 60 MPH during this entire trip. While significant damage to the trailer typically experienced with tread loss on 5th wheel trailer tire, and I have since replaced all 4 tires on the trailer with tires from your competitor Michlean XPS Highway rib tires that I certainly now have much more faith in there reliablity because of past use.



I am not seeking compensation for tires or damage you will be relieved to hear. Perhaps the tires where provided by Keystone for the wrong application I am not sure that is between you and them. I am saying myself, anyone I know, plus posting in Turbo Diesel Registry and Good Sam forums I am saying I would personally never purchase a General Tire for use in any RV applications because of the problems I have experianced and the possible safety hazard of tread seperation.



Please feel free to respond and would be happy to include any reponses to this email along with my comments to several internet forums I participate in.

 

[EricBu12]

Bob,



At least you had a name brand tire on your Keystone... . Mine, keystone Raptor, had 6 "Mission" tires which I found out to be made in W. Taipei Taiwan!!... . had 2 blowouts in 2 years and 3 more were separated but not blown yet! ...



Changed all 6 to Road Master. . which is made by Goodyear in canada ad the first trip was much better in tire temperature and such... have heard and my dad has too over the years... that running like 3 to 5 psi cold higher than max if close to the max load will help the tire life and be cooler... especially in the hot temps outside we have...



But yeah, to all, run max on all trailer tires. . doesn't hurt.

 

[Larry Willard]

Another point no one has mentioned is most RV's carry more weight on one side than the other. Look at the added weight for the slides on the street side. Another thing is as the trailer leans side to side and water sloshes, you are adding weight to one side and subtracting from the other. There fore I always run mine at 110 psi.

Larry

 

[Bob Cochran]

Max tire pressure on mine is 85 PSI for the General tires and the Michlean as well. Lots of reasons for running max as Larry Willard pointed out. I think if the tires and been a no name I would have replace sooner but did not because they was General tires. Was going to rpeace after this trip I guess I shoul have before!!! Thanks for responses.

 

[PatrickCampbell]

My trailer has 3 torsion axles and sometimes 2 of the axles won't even touch the ground. Bad design I think and Dexter specifically recommends against more than 2 torsion axles because of this. That being said on the trailer I run at 80psi on all 6.

 

[SnoKing]

My friend just returned from an Alaska trip with three broken shocks and 4 broken shackles on his Montana. He probably had 80 lbs of air in his tires, causing the suppension to have to handle greater impacts, where 65 is called for on the pressure charts. SNOKING

 

[CB HUNTER]

I pull 14,500 fifth wheel Cardinal and I alwways run max air pressure in my

rear tire of my truck and max on my trailer. I have had some bad luck on tires blowing

at low air pressure when i have weighted down the trailer in the past.

 

[PatrickCampbell]

Lets say you know the max. load that is going to be on an axle.



And by the load range vs tire inflation chart you know the max load that the tires can take at X psi, where do you inflate the tire in relation to your load.



For example, my car trailer loaded up to "max" is about 19,000 lbs (trailer weight), figure 4750 lbs pin weight. Plus say 2200 pounds on the tires just for the truck itself. Call it 7000 lbs. divided by 4 is only 1750 lbs per tire. In dual configuration, this only calls for ~43 PSI.



A few things to think about. ,...



1) Sometimes on a dually Only 3, or even 2 of those tires are touching the ground... think truck ruts...



2) at 43 PSI I am at the "MAX LOAD" per tire. How much padding/safety should I give it?

 

[EricBu12]

The padding or safety of the load chart is 1 or 2 notches up. So maybe instead of 43#. . go to 55# and you will be safe... if 65 is the max and you are loaded, this means you will have lower temperatures running. . Maybe a little more running in the center of the tire but you will have less road resistance and better mileage.

 

[WestTN]

You won't have a problem with wearing the center of the tire due to higher inflation pressure if they are a: radials and b: on the correct size rim. Oversize tires wear in the middle because their cross section width exceeds the rims.