sorry but I am new to this: ...80PSI????

[totosparents]

I was reading the tag on the side of our 5er and saw that tire pressure should be 80 PSI cold. I checked them and they were at 60 PSI. I added some air up to 72 PSI...........Just wondering if 80 is correct.



Like I said in the header, sorry for all the questions, but this is all pretty new to me
hate to be a PITA

 

[danemayer]

Hi totosparents,

If you had actual weight of the rig at each wheel, and all were below your GVWR, you could use the tire manufacturer's inflation/load charts to set the inflation to less than 80psi. But since most people don't have that information, the simpler thing is to inflate the tires to the cold inflation pressure specified on the sidewall of the tire. If you have the original tires that came on your trailer, the tag on the side should match the sidewall info.

That's the long way of saying you should inflate the tires to 80 psi when outside temps are around 70 F, you haven't towed for a few hours, and the sun is not shining directly on the tires.

One other thing. A tire that is under inflated by 20% is considered by tire manufacturers to have been "run flat", which may have caused permanent internal damage to the fibers. The damage can show up unexpectedly in the future. Goodyear suggests having their tires inspected by a Goodyear professional if they have been run 20% under inflated.

60 psi would be more than 20% under inflated. If your trailer was loaded very lightly, with no water, you might be ok. If you were loaded heavy, you might have a problem.

 

[branson4020]

Get 'em up to 80 PSI cold. Underinflation kills tires and maye you.

 

[Zedd]

Double check the side of the TIRE before putting up to 80psi just to be safe.

 

[Jim.Allison]

Double check the side of the tire and if it says Towmax, replace them and sell them to your landscaper because they will pop.

 

[Bob&Patty]

X2 on what Jim said. If they are Towmax...get rid of them ASAP. The Goodyear G614 is a great tire (not cheap) but neither is replacing the side of the trailer. Check the inside of the rim to make sure that they are rated for a 110# tire.

 

[Gaffer]

How many miles do you have @ 60 psi? If you don't know then you are driving on ticking time bombs. Low pressure and hot weather are a deadly combination that quickly kills even good tires. Run, don't walk to your nearest Discount (aka Americas) tire store and get Maxxis if Goodyear G614's are not in your budget. Check your load rate E tires every morning you tow to be sure you have 80 psi. Do not get Goodyear Marathons as they are no better than the Towmax IMHO.

 

[Grey Ghost]

Low tire pressure is like a time bomb waiting to explode and if you are running with TowMax tires that is doubled! First get rid of the TowMax tires and make sure to run the new tires with 80 psi. Keep them at 80 psi (cold) and you should be fine. Which new tire is a matter of preference, I prefer to run with Michelin LT tires on my rig, some people don't like to use LT tires, I've found them to work just GREAT for me on two separate rigs. First was a very heavy Alfa Sun and my present rig is a Heartland GreyStone 29mk which we just love! I'm running Michelin LT mt2/s and so far NO problems on the Alfa I ran with RIBS and they were great. The Greystone doesn't weigh as much and we never run with water full so I'm way below weigh limit per tire. Like I said brand and type (LT or ST) is a choice, just get rid of the TowMax tires!! Have fun, enjoy and be safe out there!!

 

[totosparents]

How many miles do you have @ 60 psi? If you don't know then you are driving on ticking time bombs. Low pressure and hot weather are a deadly combination that quickly kills even good tires. Run, don't walk to your nearest Discount (aka Americas) tire store and get Maxxis if Goodyear G614's are not in your budget. Check your load rate E tires every morning you tow to be sure you have 80 psi. Do not get Goodyear Marathons as they are no better than the Towmax IMHO.

I imagine it was shipped from Indiana to Arkansas with the 60 PSI. We just bought it this month and have only put about 60 miles on it. All this talk about them blowing and tearing up the trailer has me afraid to go anywhere with the rig. We are lucky to to have some great campgrounds near, but would really like to branch out to other states. Guess I better look into better tires. Thanks for the reply's.

 

[Jim.Allison]

Get yourself a set of LTs for that rig, never look back. ST tires are just...........well lets leave it at that.

 

[xlrEAGLE1]

I know some on here like to run their tires lower than the maximum cold pressure stated on their sidewalls, depending on load/cargo weights, but I ALWAYS run mine at their maximum cold pressure. I don't have issues with tire failure and don't notice more wear on the center of the tire than normal. To be honest, the average RV'er will (or should) replace their tires due to age or weather long before they wear out anyways. And don't forget what "cold pressure" is: it is at least 4 hours of being parked, and is not related to the ambient tempurature outside. I also keep my tires covered to prevent UV damage, park on boards instaed of asphalt, keep the weight off of them and maintain their air pressure when storing my coach. None of this gaurantees you won't experience tire failure, but it all increases your odds of having happy trips!

 

[danemayer]

Hi xlrEAGLE1,

and is not related to the ambient tempurature outside.

I believe max cold pressure is based on 70 F ambient temp, not having driven for a few hours, and tires not in direct sun. If ambient temp is higher or lower, there's about a 2% change for each 10 degrees (F). So at 30 (F) ambient, max cold pressure would be about 8% lower than normal.

On a load range G tire with sidewall max cold pressure of 110 psi, at 30 (F), if the gauge shows 101 psi, the tire is at max cold pressure and doesn't need to have air added.

Here's a link to more information from Goodyear.

 

[tireman9]

Hi totosparents,

If you had actual weight of the rig at each wheel, and all were below your GVWR, you could use the tire manufacturer's inflation/load charts to set the inflation to less than 80psi. But since most people don't have that information, the simpler thing is to inflate the tires to the cold inflation pressure specified on the sidewall of the tire. If you have the original tires that came on your trailer, the tag on the side should match the sidewall info.

That's the long way of saying you should inflate the tires to 80 psi when outside temps are around 70 F, you haven't towed for a few hours, and the sun is not shining directly on the tires.

One other thing. A tire that is under inflated by 20% is considered by tire manufacturers to have been "run flat", which may have caused permanent internal damage to the fibers. The damage can show up unexpectedly in the future. Goodyear suggests having their tires inspected by a Goodyear professional if they have been run 20% under inflated.

60 psi would be more than 20% under inflated. If your trailer was loaded very lightly, with no water, you might be ok. If you were loaded heavy, you might have a problem.

A few items I think are not supported by tire engineering facts. Some statements may not be clear.

GVWR is Gross Vehicle Weigh Rating which includes both axles and tongue weight. The figure you need id GAWR or Gross Axle weight rating. You divide this number by two and need to ensure neither tire has more than that figure (more than 90% would be better and give you a safety margin)

Trailers are not the same as Motorhomes when it comes to learning the proper cold inflation. Trailers even if they had the same load, tire size and inflation place about 24% higher "Interply Shear" on the tires than a motorhome would. As a result trailers should run tire inflation at the inflation molded on the tire sidewall associated with the max load.

RE 70F That is a Laboratory Standard many learned in High School Chemistry. That DOES NOT apply to tires. Tire pressure should be set when tires are at prevailing ambient temperature. This means not driven on for a minimum of two hours (3 better) and not in the Sun for two hours (3 better). You should use a digital gauge and not simply toss the gauge in the bottom of your tool box. At three previous rallies I tested about 60 gauges and find about 15% are off by more than 5 psi at 80 psi.

You are correct that running 20% low on air is considered to be flat.

One final point ST type tires are rated at a MAX of 65 mph. This doesn't mean average but MAX ever. Think of this as you would the red line on your truck engine tach. You may be able to run the engine faster than red line but not for long and you will pay the price sooner or later.

 

[tireman9]

Get yourself a set of LTs for that rig, never look back. ST tires are just...........well lets leave it at that.

You are correct BUT you have to do complete and proper research

 

[danemayer]

RE 70F That is a Laboratory Standard many learned in High School Chemistry. That DOES NOT apply to tires. Tire pressure should be set when tires are at prevailing ambient temperature.

Hi Tireman9,

I'm afraid I don't know how to interpret "prevailing ambient temperature".

Does that mean set tire pressure in the morning based on the weather forecast for the afternoon rather than on the actual ambient temperature? Or is there another interpretation?

When I leave Breckenridge, CO at 9 AM in late February with ambient temp at 0 (F), knowing that temps will be around 30 (F) in the afternoon, should I inflate the tires to 110 psi even though if my departure is delayed a few hours, by the time I leave, the pressure may have climbed to 116 psi?

What do I do along the way from Colorado to Texas as afternoon temps are expected to go from 30 to 50 to 70 (F)? Do I inflate to 100 psi in Colorado, knowing that by the time I get to Texas, the warmer temps will cause the tires to show inflation of 110 psi? Or do I inflate to 110 psi in Colorado knowing that the tires may show 120-125 psi on my first morning in Texas?

Does "prevailing ambient temperature" have a definition that can be used to provide practical guidance?

 

[Jim.Allison]

The best thing to do is have a tire that has load ratings at at given pressures, and a TPMS. This way you don't have to worry about changes in altitude/barometric pressure and temperature.

Tire manufacturers understand that no tire owner is going to adjust pressures each day. IMHO tires should be checked for PSI frequently (corrected if necessary) and adjusted seasonally notwithstanding dramatic changes in temperatures or altitudes or both. If a correction is required then steps should be taken to determine the reason for the loss.

It would not make much sense that 2 rigs leaving the same RV park heading for the same destination at different times, and the rig that left before daylight adjusting 1 psi up to 80 while the rig leaving at 9 AM adjusting down 1 psi to 80 psi.

If I were dead heading out of the Yukon to Phoenix AZ, I would check and adjust daily before moving my rig. TV and fiver.

 

[xlrEAGLE1]

Frome Tireman9's blog:

"With my background as a tire design engineer for a major tire manufacturer for 32 years and after working in the "Quality Assurance" department for 8 more years"

Impressive Tireman9

 

[xlrEAGLE1]

So Tireman9, even though the GVW weight of my coach is well below what 4 of my G614's can handle (maximum load each of 3750 @ 110psi ), from what you are saying, I should just keep them set at 110 psi and not worry about the load charts? And if my rims are stamped "110psi", should they have enough of a tolerance built into them to handle the psi fluxuation of the tire (as it heats up and cools down) if I am at 110 psi "cold"? I am leaning towards running them at 110 psi and monitoring them more often.

The rep I spoke with at Good Year encouraged me to run them at 110psi, regardless of load, and from what I gathered in your earlier post, you are saying the same thing.

If so, I know it will require me to monitor the psi more often, but I am good with that as long as I will be able to limit tire issues!

 

[jnbhobe]

Set and maintain your tires at 110 psi. Use your RV and enjoy it, do you change the pressure on your car tires every time the temps change??

 

[xlrEAGLE1]

Set and maintain your tires at 110 psi. Use your RV and enjoy it, do you change the pressure on your car tires every time the temps change??

Yea, I just found this on Tireman9's blog, which answers the questions I asked him below, except for the rim tolerance: "So the best recommendation I can give to trailer owners is to run the inflation molded on the tire sidewall. For owners of a TV or motorhomes, I recommend you run the inflation needed to carry the actual measured tire load plus at least a 10% margin."

By the way, if you haven't read his blog, it is very informative. I have learned alot form it.