Community Forums

mhedlund · 08-25-2012, 06:57 AM

I need some input on tire pressure. I have a Heartland Big Horn 5th wheel and I run ST235/80 R16E tires. I had a new set of Goodyear Marathons put on less than 2 years ago. I keep them inflated at 80 psi and monitor the pressure with a Pressure Pro monitoring system. When parked, they are off concrete and covered. Normally on the road the pressure will increase to 87-89 while rolling. This last trip, I had one showing at 94 and when we stopped the center belt had separated. After replacing the tire, I asked about tire pressure and heat build up. It was suggested that maybe I lower my cold pressure to about 75 psi so the heat build up would be closer to the 80 psi. This didn't sound quite right to me so I asking for some feed back. Thanks

ga traveler · 08-25-2012, 07:01 AM

I have read hundreds of tire publications and every single one says to check the tires when cold and adjust at cold temps.

RustyJC · 08-25-2012, 07:02 AM

Quote:

Originally Posted by mhedlund

It was suggested that maybe I lower my cold pressure to about 75 psi so the heat build up would be closer to the 80 psi. This didn't sound quite right to me so I asking for some feed back. Thanks

Bad suggestion!!

Set the cold inflation pressure to the manufacturer's specification as shown in the appropriate load/inflation table. That specification takes into account the pressure increase due to heat buildup when running.

Rusty

az bound · 08-25-2012, 07:17 AM

I would even bet that on the side of the tire it says the pressure is to be checked cold.
I have talked to some at rest stops that were lowering the pressure because they said it was too high. Bad idea, and dangerous also.

Sky_Boss · 08-25-2012, 07:28 AM

NO NO NO...

Do NOT adjust cold tire pressure because the manufacturer build that into the whole equation. There are some consideration for driving from low altitudes into high altitudes but unless you over inflate a tire in the first place, I doubt it should be a serious consideration.

Tire tread separation is not always do to inflation practices...tires do fail. Tire quality and ratings do apply.

Also, reduced tire pressure increases tire temp thus increasing pressure on the road. Over inflation can reduce temps thus minimizing temperature induced pressure increase.. Kind of a strange yin-yang thing. LOL

mhedlund · 08-25-2012, 02:30 PM

I appreciate all the feedback. That was what I was thinking, just needed some backup

JIMNLIN · 08-26-2012, 01:21 PM

I've had many flatdeck trailers in commercial service on the road 24/7 at max axle loads or empty or in between. I found max sidewall pressures worked best for the tires long term reliability.

Nothing unusual about a Marathon or any ST tire to show split tread belts or tread separation. A tire type change to LTs will fix those issues.

Goodyear says this about pressures for tires on a trailer :

Goodyear Tire and Rubber .... weighing RVs
Special Considerations
Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up.

smiller · 08-26-2012, 01:34 PM

Quote:

Originally Posted by JIMNLIN

Nothing unusual about a Marathon or any ST tire to show split tread belts or tread separation.

It is not correct to say that 'any ST tire' will have problems. Poor examples will have problems and good examples will not, just as with an LT or any other type of tire.

JIMNLIN · 08-26-2012, 08:07 PM

Quote:

Originally Posted by smiller

It is not correct to say that 'any ST tire' will have problems. Poor examples will have problems and good examples will not, just as with an LT or any other type of tire.

Its been my experience a ST tires are a poor example of a tire for a trailer the size the OP is about. Yours may be different.

caissiel · 09-03-2012, 06:41 PM

I have Tire pressure monitors on my Big Country Trailer Tires and observe the pressures closely. The cold pressure tire that reads lower on the begining of a trip will always read high pressures when hot and the temperature will be also higher.

So never lower the pressure as it will surely increase the hot temperature and pressure. And surely lead to premature failure. I always trust my PMS system have learn lots and at the price for valve stem mounted systems there is no excuse not to own it. Its cheaper then a Tire and the results could surely be peace of mind and understanding.

My 110 PSI cold tires run at 123 PSI under normal condition and if at 108 PSI or lower sometimes will reach higher pressures and much higher temperatures.

mhedlund · 09-04-2012, 05:35 AM

Thank you all for you input and replies

JohnBoyToo · 09-04-2012, 07:24 AM

Hedlund ?!?

Are you related to our currently houseless friends living at Mill Creek in their nice Heartland ?!?!
(They are houseless because they chose to sell their house and looking for another

)

***************
couple of points I've learned in my mistakes

apologies if you know this already !
lower pressure builds more heat in the tires since each revolution they have to flex more (note how really low tires 'bulge' at the bottom? and they are straighter at the top? the rubber has to deform EACH revolution which generates a lot of heat)

**************************************
You will find that your psi WILL change over time... be it temperature changes, heating from the sun, heating from driving or cooling from stopping, etc...

Some good teachers suggested I check psi each stop, and on our last trip while filling up, I checked tires and found they were down a few psi.. so filled them up to 80 psi cold as called for on the sidewall.

drove on, unloaded at home, brought it to storage area, and a few days later measured psi... one was @ 70 psi !!!!
so next time out
I will measure them again and note what each tire is at so I can subtract from 80 psi, drive straight to the closest air pump (since my little portable won't air up large tires), measure the tires again and
add the difference to their warmed up psi..

I know, I know, get a better air pump, and get a tire monitoring system

want to, just haven't justified the expense with the few trips this first year...

Dunner · 09-04-2012, 09:44 AM

I always checked the PSIs on my 5er before and during every trip and went through 5 brands of ST tires with blow outs and separations. When I changed to LT tires, I never had another tire problem.

mhedlund · 09-05-2012, 05:35 AM

JohnBoyToo, I don't think I'm related to those currently at Mill Creek. I check and inflate my tires before I leave the house. At each stop, I check and inflate (if needed). I carry a Porter Cable pancake compressor in my rig with the tank full (just in case I would need it and not have electricity), I use a Pro Pressure Monitoring system and check the pressure readings regularly in route. The monitoring system has a low pressure alert.
This last trip (only 2 1/2) hours, we noticed that one tire was running about 5 pounds higher than the other three. When we got to our stop, I found the tire with the higher pressure had slipped a belt. I carry two spares and changed one of them for the bad tire. On our return trip, we noticed the same thing on another tire (not quite as high though) and when we got home, I found that tire had also started to slip a belt)
My Heartland Big Horn has 6000 lp axles and I run Goodyear Marathon tires. Some have suggested changing to a LT tire. Does anyone know it that would that take new wheels? This tire thing has been a concern since we have had two blow outs in 2010 (and before the Goodyear, compressor, monitoring system and two spare rack)