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Old 04-19-2019, 06:54 PM   #1
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Tire pressure

New front tires...sidewall says 120 psi. docs in the coach say 82 psi. The mechanic at the tire company insisted 120 was correct, but I've always thought the Thor numbers should be followed. I'm thinking around 90.
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Old 04-19-2019, 09:20 PM   #2
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Weight is the only way to be sure of psig, scale, tire chart and decrease if the chart says so

The sticker weight is a guesstimate
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Old 04-19-2019, 09:35 PM   #3
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The pressure on the sidewall is the maximum allowable for the tire at it's maximum load. There are tire charts that convert the weight to the proper tire pressure. Goodyear and Michelin have charts on their websites, but you need to have your coach weighed to get the proper air pressure.
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Old 04-19-2019, 10:08 PM   #4
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You donít have your coach listed or the size and make of your tires. If you list them, someone will probably send you or direct you to the website that has the chart for those tires. Correct tire pressure is crucial to the handling and safety of your coach and to the wear of your tires. The only way you can know your correct tire pressure for sure is to load your coach like you intend to travel in it and go weigh your coach both front and rear. Some weigh all four corners separately, but unless you have some reason to think that one side is way different than the other - that is probably not necessary. With the front and rear weight measurements, you can then go to the tire charts and see what the tire manufacturer recommends. I think that a set of Tire Minders or similar equipment to constantly measure your tire pressures and temperatures is a necessary safety feature - if your coach is not already so equipped. All my cars have this as standard equipment and a blow out is so much more dangerous in an RV than a car. I donít know the RV manufactures get away with not providing it as standard on all RVs.
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Old 04-19-2019, 10:50 PM   #5
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Originally Posted by Mitch S View Post
The pressure on the sidewall is the maximum allowable for the tire at it's maximum load. .
I agree...
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Old 04-20-2019, 12:45 AM   #6
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The pressure on the sidewall is the maximum allowable for the tire at it's maximum load. There are tire charts that convert the weight to the proper tire pressure. Goodyear and Michelin have charts on their websites, but you need to have your coach weighed to get the proper air pressure.
The sidewall psig stamp is the minimum pressure for the maximum load stated

Cold psig as it will go up when operating in hot weather
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Old 04-20-2019, 02:11 AM   #7
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Originally Posted by lwmcguire View Post
The sidewall psig stamp is the minimum pressure for the maximum load stated

Cold psig as it will go up when operating in hot weather
No. The Psi tire pressure embossed on the side of the tire is the maximum cold psi that the tire is designed to hold, whether it is under any load or not. That tire and that pressure determines what safe load the tire can carry. Most tires are not (and donít need to be) filled to max pressure. The psi in the tire will increase as the ambient air temperature increases or as you run your tires and heat them up. The front tires in my RV should be run at 80 psi or max pressure for my Michelin tires to carry the 4000lbs of weight load on the two front tires. When I travel south in the late fall, I fill those tires to 80 psi at about 50 degrees F. As I travel south and the ambient air temp increases to 60 and 70, I have to let air out of the tires in the morning to keep them below 80 psi because the psi increases with the ambient temp. When I run my tires at 70 mph on a hot road, my Tire Minders will tell me that the temp in my tires has increased from the ambient temperature to 90-100 degrees and the psi will rise 5 lbs or more. That is what the tire is designed for.
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Old 04-20-2019, 02:29 AM   #8
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Use the pressures on the yellow sticker until you get your coach weighed and then adjust as necessary.

And steer clear of that "mechanic".
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Old 04-20-2019, 02:59 AM   #9
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First: welcome to the forum.

Second: Met a Seaweed in Oak Island a couple years ago during a PGR Vietnam Wall escort with the Grand Dude. You the same person?

Third: Recommend you go to the first link on this forum and download Ed's great handbook. If you don't have a Axis/Vegas you can still use a lot of it for your particular RV.

Fourth: 75 front/65 rear are basic values for Axis/Vegas RV.
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Old 04-22-2019, 03:27 AM   #10
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Thanks to all for the info...I'll get front and rear weights shortly and check the charts. It's a 2014 ACE 29.2, and 82 psi is the number for now.
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Old 10-26-2019, 11:24 PM   #11
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Tire psi

Took my 2018 Hurricane M 29 in for an alignment and the mechanic set my tires to 110 psi, he said that is the recommended psi, the coach sticker says they should be 85 psi. I was told if you donít run the at the recommended psi you could have a lot of problems with the tires. Any thoughts.
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Old 10-26-2019, 11:46 PM   #12
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Took my 2018 Hurricane M 29 in for an alignment and the mechanic set my tires to 110 psi, he said that is the recommended psi, the coach sticker says they should be 85 psi. I was told if you donít run the at the recommended psi you could have a lot of problems with the tires. Any thoughts.
Get a new alignment tech.
Just because the MAX pressure on the sidewall is 110 PSI does not mean that is the recommended pressure.
Without an accurate coach weight you should follow the MANUFACTURER's recommendation of 85 PSI on the coach sticker.
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Old 10-27-2019, 12:27 AM   #13
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Third: Recommend you go to the first link on this forum and download Ed's great handbook. If you don't have a Axis/Vegas you can still use a lot of it for your particular RV.
Cal - I tried to find this but canít. Would you mind sending a link? Thank you in advance!
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Old 10-29-2019, 07:35 PM   #14
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Originally Posted by Oneilkeys View Post
No. The Psi tire pressure embossed on the side of the tire is the maximum cold psi that the tire is designed to hold, whether it is under any load or not. That tire and that pressure determines what safe load the tire can carry. Most tires are not (and donít need to be) filled to max pressure. The psi in the tire will increase as the ambient air temperature increases or as you run your tires and heat them up. The front tires in my RV should be run at 80 psi or max pressure for my Michelin tires to carry the 4000lbs of weight load on the two front tires. When I travel south in the late fall, I fill those tires to 80 psi at about 50 degrees F. As I travel south and the ambient air temp increases to 60 and 70, I have to let air out of the tires in the morning to keep them below 80 psi because the psi increases with the ambient temp. When I run my tires at 70 mph on a hot road, my Tire Minders will tell me that the temp in my tires has increased from the ambient temperature to 90-100 degrees and the psi will rise 5 lbs or more. That is what the tire is designed for.
Well you are partially right in that is the starting point when airing up the tire

The stamped pressure is actually the minimum for the maximum load because of what you brought up (I did not state anywhere to inflate above the sidewall psig)

If you are driving and the tires heat up as they do and the pressure increased accordingly then you are now operating your tires lets say with 90 psig which isn't now the minimum pressure but is the new pressure due to the increase from the tire operation flexing from the load and the ambient temperature

In other words you don't stop and let the pressure back down to 80 as the tires heated up and increased the pressure, you keep on driving. That

Setting the pressure cold is correct based on the maximum tire load
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Old 10-29-2019, 10:40 PM   #15
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Rated pressure vs. running pressure

I just had an rv inspected. Inspector said that the tires were rated for 115 and the tires were inflated to 75. He suggested that if I inflated them to 100 Iíd see better handling, mpg and less wear.

Does that sound right? I havenít seen the docs inside the rv - I fly tomorrow from check it out.

Itís a 2017 THOR outlaw 38re.
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Old 10-29-2019, 11:37 PM   #16
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To little pressure will definitely do all that was noted

Weight per axle is the only true accurate means to determine ideal psig

75 definitely sounds to low

Mine wonders around and is dangerous on curves when pressure is too low
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Old 10-29-2019, 11:42 PM   #17
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Originally Posted by WearyTraveler View Post
I just had an rv inspected. Inspector said that the tires were rated for 115 and the tires were inflated to 75. He suggested that if I inflated them to 100 Iíd see better handling, mpg and less wear.

Does that sound right? I havenít seen the docs inside the rv - I fly tomorrow from check it out.

Itís a 2017 THOR outlaw 38re.
Good luck, and happy hunting!
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Old 10-31-2019, 10:27 PM   #18
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Originally Posted by lwmcguire View Post
Weight is the only way to be sure of psig, scale, tire chart and decrease if the chart says so

The sticker weight is a guesstimate
The problem with the sticker weight is it only references the tires used when departed from the factory. McGuire is correct - reference the chart for your weight, particularly if you switch brands.
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Old 10-31-2019, 10:37 PM   #19
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Originally Posted by lwmcguire View Post
To little pressure will definitely do all that was noted

Weight per axle is the only true accurate means to determine ideal psig

75 definitely sounds to low

Mine wonders around and is dangerous on curves when pressure is too low
You can go nuts with stuff and some would argue the coach is not 'balanced' and all four corners will be something different. I'm not going to obsess that far. 7200mi on a set of Michelins. I use the door jamb sticker.
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Old 11-01-2019, 06:28 PM   #20
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The real world way to tell if you are underinflated is to monitor the tire temperature. If you have tires you can't hold you hand on when driving in hot weather you are damaging your tires.

We ran trucks and trailer for over 50 years commercially and not one time did we ever let air out of tires when running back empty. Same goes for commercial rigs now. If you are going to error then error on the higher side of inflation, not the lower.
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