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I hate to open up the tire pressure posts again, but I do not see my question posted on the forum.. I run Goodyear G 114's H rated tires on my 5th wheel. I have Dexter 9,000 lbs independent suspension axles. The max inflation is 125 psi cold. I am 99% certain that I am not overloaded. But, I have not weighed by tire/axles YET. I have a TST tire monitoring system. I inflate to 125 psi cold and after a short time going down Arizona roads at 90 degrees outside air temp. the tire pressure rises to 140 psi. The tire temperature registered on the monitor is about 95 degrees. My question is; IS that high of pressure normal? Are the tires designed to handle 140-145 PSI while going down the highway? Any help and or guidance to more information would be appreciated.
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Jeff, Gwen and Bella
2017 DRV Mobile Suites 40 KSSB4
2012 DRV Mobile Suites 36 RSSB3 (sold)
2011 Ford F450 (BO)
2013 Ford F150 (Red)
Cargo Trailer for Gold Wing, Golf Clubs, Bicycles and Cast Iron Soup Pot!
Thanks for your response. Two axle. My coach is a DRV MS 40kssb4,, gvwr is 21,000#.. I had a DRV MS 36rssb3 gvwr 18,500#. I had it axle weighed and it was right on the gross weight. Not over axle. All of our stuff from the old coach went into the new one. We have not added anything, so that is why I am confident we should not be over weight. The new coach has more cargo carrying capacity.
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Jeff, Gwen and Bella
2017 DRV Mobile Suites 40 KSSB4
2012 DRV Mobile Suites 36 RSSB3 (sold)
2011 Ford F450 (BO)
2013 Ford F150 (Red)
Cargo Trailer for Gold Wing, Golf Clubs, Bicycles and Cast Iron Soup Pot!
Does running a TT tire at any pressure other than the manufacturer's recommended pressure void any warranty or liability? I believe yes.
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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
Does running a TT tire at any pressure other than the manufacturer's recommended pressure void any warranty or liability? I believe yes.
Most all tire manufacturers have weight/inflation charts for each tire. GY Tech Support says to weigh each tire if possible then use the heaviest tire on each axle and compare to the inflation chart then add 5psi to the recommended psi. So basically inflate both tires on each axle the same based on heaviest tire.
America's Tire Store - "A trailer tire should be inflated to the maximum inflation designated on the sidewall of the tire."
Etrailer - "Trailer tires should be kept inflated to the maximum pressure listed on the tire sidewall"
Trailer Life - "Tires should be inflated to the pressure recommended for the trailer."
West Marine - "Maintain pressure at the maximum PSI recommended on the tire’s sidewall for cool running, load-carrying ability and lowest rolling resistance"
The Fit RV - "The first is simply inflating all the tires to the maximum pressure listed on the sidewall."
Les Schwab Tires - "Keeping them at the full PSI (pounds per square inch) pressure is key for longevity, load-carrying ability, cool running and best fuel economy."
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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
As for your original question about the pressure variance while driving, 140 - 145 psi on those tires is not a problem. It is normal. Many of the tire pressure monitoring systems have a factory upper limit alert set at 12.5% of the base tire pressure. That would be 15.6 psi over your 125 psi or about 141 psi. Another 5 psi over that won't hurt. On an 80 psi E load range tire, 15 - 20 psi over the max would be more concerning.
As for the other issue, generally it is recommended to run maximum sidewall pressure on trailer tires. That's because most trailer tires are near their maximum load capacity anyway, and it helps take pressure off the sidewalls of the tires because there is more scuffing and skidding of trailer tires in sharp turns and backing situations.
However, in cases where the tires have WAY more capacity than the loads they are carrying (often the case with the Goodyear G114s), then it is just fine (and recommended) to use lower pressures that are more in line with the actual load being carried.
As others have replied…inflate your tires based on the load on them and not the maximum cold pressure…find the heaviest wheel, look up the appropriate pressure for that weight, add 5 and put that in all of the trailer tires. Overinflating them to max can result in uneven tire wear in the center of the tread. You can completely disregard the advice from tire companies to always inflate to maximum…that is the easiest thing for them to recommend and helps them sell tires faster due to overwear. Howard's not about max pressure due to being almost fully loaded is spot on…builders put the cheapest (and therefore least load capable) tires on the rig that they can get away with.
My trailer tires (H114's like you) I inflate to 105 cold based on load on them. At freeway speeds in the summer they're up in the mid 120s. The truck tires (RAM 5500) go from 98-100 up to 110 or so.
Max pressure…might void your warranty if they could prove you did it…but running at a lower pressure (for a better ride) as long as it's the appropriate pressure for the weight on it is just fine.
Let me add a little to this discussion. "Inflate TRAILER TIRES to maximum" ... that is generally true. "Trailer Tires"" size designator begins with ST (Special Trailer). This what most OEMs use and should be inflated to the maximum (cold) pressure on the side wall, which is normally 80 PSI for E rated tires. ST tires are usually speed rated to 65 mph.
If the tire size designator begins with LT, that is a different animal. LT tires (Light Truck) are for trucks and trailers but are generally MUCH stronger (more plies, more steel belts) than ST and have a speed rating that is higher, often 75 mph, as is the case with your G114's. The advice given about using the inflation charts is spot on for LT tires.
-- Edited by RonC on Thursday 25th of May 2017 09:23:36 AM
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Ron and Janice
2016 Ford F350, King Ranch, DRW, 4x4, CC, 6.7 PS Diesel, remote control air lift system
2017 Durango Gold 381REF, Lambright furniture, MCD shades, morRYDE IS, 8K Disc brakes, GY G114 LR H Tires, 27,320 lbs CGVW
Yes, after weighing, if the tire is not carrying the max amount of weight you can run less pressure. I have reviewed the chart supplied by Goodyear. for the G114's. I guess my question is how high should the pressure go up while travelling down the highway? What are the tires designed for?
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Jeff, Gwen and Bella
2017 DRV Mobile Suites 40 KSSB4
2012 DRV Mobile Suites 36 RSSB3 (sold)
2011 Ford F450 (BO)
2013 Ford F150 (Red)
Cargo Trailer for Gold Wing, Golf Clubs, Bicycles and Cast Iron Soup Pot!
Thanks everyone and Howard for your information. Bottom line is I need to get the coach weighed by axle in order to know the exact correct pressure to run. I will now be looking for a rally that provides axle weighing, so I can plan on attending. Safe travels everyone.
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Jeff, Gwen and Bella
2017 DRV Mobile Suites 40 KSSB4
2012 DRV Mobile Suites 36 RSSB3 (sold)
2011 Ford F450 (BO)
2013 Ford F150 (Red)
Cargo Trailer for Gold Wing, Golf Clubs, Bicycles and Cast Iron Soup Pot!
Actually, you should get it weighed wheel by wheel. An 8,000 lbs axle really means that each tire position is rated at 4,000 lbs. It is possible to be at 8,000 lbs on an axle, but overweight on one of tires.
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Ron and Janice
2016 Ford F350, King Ranch, DRW, 4x4, CC, 6.7 PS Diesel, remote control air lift system
2017 Durango Gold 381REF, Lambright furniture, MCD shades, morRYDE IS, 8K Disc brakes, GY G114 LR H Tires, 27,320 lbs CGVW
First the reason most places recommend inflating the tires to the maximum is simple - most people don't regularly check their pressures. Plus, these same people don't know how much weight is on each tire. As is the case that you need to know how much weight you are carrying you can then match the correct pressure to the weight. Keep in mind if you vary your water or holding tanks this can impact one or more tires.
On the discussion about "ST" and "LT" the main differences are tire compounding, tread depth (more is not necessarily better), and also tread design. As to the misnomer of the "LT" being stronger this is not necessarily true. When you look at the construction of the two you will see both have typically a polyester body with two steel belts. The normal sidewall of a "LT" will either have and additional layer or a tougher compounding to fight penetration.
The G114 is considered a medium commercial tire. It has a steel body as opposed to the normal "ST" tire. it is designed to be a trailer use only tire. As to the increase in pressure, some increase is to be expected.
First thing I would do is to take you tire gauge to a tire shop that has a master gauge to double check it is accurate. Second, I would then double check you psi when the tires are warm to verify your gauge and TPMS system match. What every you do DO NOT DEFLATE YOUR TIRES WARM. Tire pressure should always be checked "cold". Cold in the tire business means when the temp inside the tire is at ambient temperature. Even going a couple of miles will increase the temperature in the tire.
To the OP ... if you have the TST 507 tire pressure and temperature monitor, the set up instructions tell you to set the low pressure alarm at 5 psi lower than the cold pressure and and the high pressure alarm at 20 psi over the cold pressure. It comes factory preset at 158 degrees for the high temp alarm. They say that according to Michelin, high temp failures typically occur at 180-200 degrees. While that information does not directly answer your question, it does suggest that temps up to 158 should be safe (based on where they preset the high temp warning).
-- Edited by RonC on Thursday 25th of May 2017 09:55:06 AM
-- Edited by RonC on Thursday 25th of May 2017 09:56:56 AM
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Ron and Janice
2016 Ford F350, King Ranch, DRW, 4x4, CC, 6.7 PS Diesel, remote control air lift system
2017 Durango Gold 381REF, Lambright furniture, MCD shades, morRYDE IS, 8K Disc brakes, GY G114 LR H Tires, 27,320 lbs CGVW
To the OP ... if you have the TST 507 tire pressure and temperature monitor, the set up instructions tell you to set the low pressure alarm at 5 psi lower than the cold pressure and and the high pressure alarm at 20 psi over the cold pressure. It comes factory preset at 158 degrees for the high temp alarm. They say that according to Michelin, high temp failures typically occur at 180-200 degrees. While that information does not directly answer your question, it does suggest that temps up to 158 should be safe (based on where they preset the high temp warning).
-- Edited by RonC on Thursday 25th of May 2017 09:55:06 AM
-- Edited by RonC on Thursday 25th of May 2017 09:56:56 AM
Hey Ron, Was that 5/20 PSI of cold pressure or percent of cold pressure? I just set mine up and have the setting based on percent, now I have to go home and double check. Of course if the cold PSI is 100 it won't make much difference.
Steve
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2017 Starcraft 26BHS Autumn Ridge TT, 2019 Chevrolet 3500 SRW Duramax 6.6 4WD TV
Plan to retire/full-time in 2021. Favorite place to camp; Texas State Parks.
Travel is fatal to prejudice, bigotry, and narrow-mindedness.. Mark Twain
It said PSI. If you go to the TST website, there is a video that shows how to set the pressures on the monitor, in that video they say 10 and 20 PSI for the low and high pressures respectively. The video is under the "How To" tab. Select installation and watch the short video.
BTW ... I MADE A MISTAKE. THE CORRECTIONS ARE THE LOW PRESSURE WARNING SHOULD BE 10 PSI BELOW THE COLD PRESSURE NOT 5 PSI AS I PREVIOUSLY SAID. EVERYTHING ELSE IS CORRECT!
Stephen,I'm glad you asked, it caused me to review my facts which is when I found my error, Thank You! -- Edited by RonC on Thursday 25th of May 2017 05:05:56 PM
-- Edited by RonC on Thursday 25th of May 2017 05:07:55 PM
-- Edited by RonC on Thursday 25th of May 2017 05:08:44 PM
-- Edited by RonC on Thursday 25th of May 2017 05:10:28 PM
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Ron and Janice
2016 Ford F350, King Ranch, DRW, 4x4, CC, 6.7 PS Diesel, remote control air lift system
2017 Durango Gold 381REF, Lambright furniture, MCD shades, morRYDE IS, 8K Disc brakes, GY G114 LR H Tires, 27,320 lbs CGVW
Okay that is interesting. I have not had a chance to see the video yet, but I have no doubt that you are correct. But their troubleshooting guide that came with my 507 says verbatim, "We recommend you set the parameters at 20% above and 10% below what you typically run your tires..." It goes on to say that during hot temps you can set 25% above to avoid unneccessary alarms. Is it possible that they are refering to something other than High/Low alarm parameters? Curious.
Now I'm going to go watch the video; I'm sure I'll learn somthing.
Steve
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2017 Starcraft 26BHS Autumn Ridge TT, 2019 Chevrolet 3500 SRW Duramax 6.6 4WD TV
Plan to retire/full-time in 2021. Favorite place to camp; Texas State Parks.
Travel is fatal to prejudice, bigotry, and narrow-mindedness.. Mark Twain
Maybe2021 .. As you pointed out, if your cold TP is 100 PSI then they are the same. And honestly, I don't think there would be a huge difference either way, probably safe using either approach.
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Ron and Janice
2016 Ford F350, King Ranch, DRW, 4x4, CC, 6.7 PS Diesel, remote control air lift system
2017 Durango Gold 381REF, Lambright furniture, MCD shades, morRYDE IS, 8K Disc brakes, GY G114 LR H Tires, 27,320 lbs CGVW
This is about the inflation pressures. I’m just going to point out how it’s supposed to happen.
With the much heavier trailers such as the one being discussed in this thread, tires may often come from different sources other than the Special Trailer (ST) tire market. Many of those tires are used in the trucking industry and over time the two very different tire governing bodies regulations have been mingled - to some degree - together. They are not compatible. Major obstacles will present themself when tires fitted in accordance with Federal Motor Carrier Safety Administration (FMCSA) vice Federal Motor Vehicle Safety Standards (FMVSS). There is no cold recommended inflation pressure provisions in the FMCSA.
All DOT highway certified tires are suitable for RV trailer fitments and that privilege is at the vehicle manufacturer’s discretion.
The Original Equipment (OE) tires fitted to the trailer in this discussion become the benchmark for all subsequent fitments. The correct inflation pressures for the OE tires is on the certification label, tire placard and in the vehicle owner’s manual. The OE tires are considered under inflated when their cold inflation pressures are below vehicle manufacturer recommendations. They are over inflated when their cold inflation pressures are above the inflation pressures listed on the tire sidewall to achieve maximum load capacity.
Replacement tires from another design or different size still use the benchmark set with the OE tires. Tire industry standards are very consistent about this. The replacement tires must provide a load capacity equal to or greater than the OE tires via inflation. NHTSA allows the use of an auxiliary tire placard for identification of plus sized tires and different inflation pressures. It can be hand made and placed adjacent to the original tire placard. Most savvy tire retailers already have blanks printed.
That’s basically how it’s supposed to be. When researching this subject you will have to read about vehicle certification and in this case FMVSS 571.120. In 571.120 you will find where NHTSA has directed the vehicle manufacturer to set cold recommended tire inflation pressures.
-- Edited by FastEagle on Thursday 1st of June 2017 08:04:37 PM
