Tire pressure

[edfgrf]

First really long trip with a tire pressure monitoring system. 16 31ul ,19.5 tires, 95psi cold pressure. When the pressure had built up both the inner rear tires was 6-7 psi higher than outside. has anyone else experienced this? Do you think this is normal?

[chasfenwick]

Originally Posted by edfgrf

First really long trip with a tire pressure monitoring system. 16 31ul ,95psi cold pressure. When the pressure had built up both the inner rear tires was 6-7 psi higher than outside. has anyone else experienced this? Do you think this is normal?

All 6 tires read 95 psi cold? . . . That doesn't track with what I've seen on my 17 31ul. Is suspicious.

[norty1]

You are asking about the dually tires on your tow vehicle?

[Allen_C]

Originally Posted by norty1

You are asking about the dually tires on your tow vehicle?

Nope, op has a Precept 31ul. Dual rear drive axle.

[Pandara]

I've noticed it on our 31UL, also when we had our Melbourne 29D and a couple of dually pickups when towing....I think it's because the inner tires are not getting the airflow the outers are,and they are closer to the brakes and the engine and exhaust heat coming back so they tend to get a bit warmer. Some think the crown of the road can put more weight on the inners, I'm not sure.....We have not had any issues with the pressure difference.

[nma33]

I have a 35UN and on my recent NJ to Yellowstone and back trip My tires started the day at 100psi each, They all stayed within 3-4 PSi at all times most often within 2 psi, It seemed that sometimes the sunny side had a slightly higher psi, also depends on the road you are on, how much of a crown is on the road. seems that if the road had a very noticeable crown the inside tires seemed to run a few psi higher then the outside. Just a few observation from 1 trip.

[edfgrf]

Thanks to all for contributing.

[Enpserrato]

New Rv'r here, 2018 precept 31ul. Is a tire monitoring system recommended.

[Allen_C]

Originally Posted by Enpserrato

New Rv'r here, 2018 precept 31ul. Is a tire monitoring system recommended.

IMHO, TPMS is desirable for all motorhomes. Knowing a tire's temp and/or pressure is changing suddenly on its own is a big signal that something is wrong and should be checked before it blows. A front tire blowout can be very dangerous.

[chasfenwick]

Originally Posted by edfgrf

First really long trip with a tire pressure monitoring system. 16 31ul ,19.5 tires, 95psi cold pressure. When the pressure had built up both the inner rear tires was 6-7 psi higher than outside. has anyone else experienced this? Do you think this is normal?

I have 17 Precept 31UL and took special note today of what the tire pressures of the dually pairs were doing as I drove down the Interstate. On both sides the pressures in the pair stayed within 1 psi of one another.

[TexasRVr]

I'm curios, what tire pressure you all are using for your Precepts? I see 95 psi listed in this thread. Any other feedback?


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[chasfenwick]

Originally Posted by TexasRVr

I'm curios, what tire pressure you all are using for your Precepts? I see 95 psi listed in this thread. Any other feedback?


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The placard on the wall next to the driver's seat says 90 psi and that's what I do. Else is to claim that I know more about it than the Ford engineers who designed the thing.

[Rvlife]

What should the tire pressure be in a 31'?

[chasfenwick]

Originally Posted by Rvlife

What should the tire pressure be in a 31'?

I am speaking solely with respect to my 2017 Precept 31UL, with the 22.5-inch tires.

[RoyB]

I am new to class A machines but have flown many different aircraft military and civilian and always start with the operator's manual. The manual for the Michelin RV tires I have on a 36A Precept with 22.5" wheels give a chart for different weights. These range from 70 to 110 depending on the weights of the axles. The pressure posted on the tires and on the placard by the drivers seat is the maximum pressure for the maximum weight. In my case the posted pressure is for a weight that is 6000 lbs more the the maximum weight of my coach. In fact, all pressures above 80 are for weights greater then my coach's 24K GVWR. So this would indicate my choices are 70 or 80 depending on how heavy I'm loaded on a given trip. Otherwise the manual tells me that being over or under inflated based on weight will give early wear on the tires.

My problem is I have not seen anyone posting here that is following this information from the manual. So what am I missing?

[Dopalgangr]

Originally Posted by RoyB

I am new to class A machines but have flown many different aircraft military and civilian and always start with the operator's manual. The manual for the Michelin RV tires I have on a 36A Precept with 22.5" wheels give a chart for different weights. These range from 70 to 110 depending on the weights of the axles. The pressure posted on the tires and on the placard by the drivers seat is the maximum pressure for the maximum weight. In my case the posted pressure is for a weight that is 6000 lbs more the the maximum weight of my coach. In fact, all pressures above 80 are for weights greater then my coach's 24K GVWR. So this would indicate my choices are 70 or 80 depending on how heavy I'm loaded on a given trip. Otherwise the manual tells me that being over or under inflated based on weight will give early wear on the tires.

My problem is I have not seen anyone posting here that is following this information from the manual. So what am I missing?

FWIW My brother-in-law is a Ford mechanic who works on these size tires a lot. He advised to always go with the placard even though its the max rating. He said that the worst thing for these tires is the wrong tire pressure and will prematurely wear them out. He did say to monitor the tire to get a feel for the added pressure when they heat up and adjust the pressure so that once heated the tire is at the placard recommendation.

I also would like to know of any brand monitor systems that anyone on here would recommend.

[NickM]

Originally Posted by RoyB

I am new to class A machines but have flown many different aircraft military and civilian and always start with the operator's manual. The manual for the Michelin RV tires I have on a 36A Precept with 22.5" wheels give a chart for different weights. These range from 70 to 110 depending on the weights of the axles. The pressure posted on the tires and on the placard by the drivers seat is the maximum pressure for the maximum weight. In my case the posted pressure is for a weight that is 6000 lbs more the the maximum weight of my coach. In fact, all pressures above 80 are for weights greater then my coach's 24K GVWR. So this would indicate my choices are 70 or 80 depending on how heavy I'm loaded on a given trip. Otherwise the manual tells me that being over or under inflated based on weight will give early wear on the tires.

My problem is I have not seen anyone posting here that is following this information from the manual. So what am I missing?

RoyB, you have it correct. Michelin has pressure versus weight charts for a good reason, they designed the tires, not Ford engineers. I have a 2016 35US and with my weight I could get in the 80 psi region if desired. Like many others I started out with 100 psi as a recommendation, supposedly to improve handling. Well, that didn't work but a good alignment did the trick so now I am playing with tire pressures. Fronts are down to 85 and rears are down to 90 and I expect to keep them at that point for out next trip to FL in January.

The Jayco placard beside the drivers seat is a CYA sticker for Jayco/Ford and while there is nothing wrong with following their guidelines your ride will improve with a lower safe pressure. I weighed my coach on a CAT scale with full gas and propane, 20 gallons fresh water and empty grey/black tanks plus all our usual travel goods. Heavy items were placed towards the front, lighter items towards the rear.

If I had an opportunity I would like to have four wheel weights but since the CAT scales don't do that I used front axle weight divided by two and rear axle weight divided by 4 to get approximate tire weights which are close enough for the Michelin charts.

Michelin has been in the tire business for a long, long time and I believe their engineers know way more about tires than Ford and Jayco so I will follow their guidelines until I learn something different.

[nhake01]

It is important to have your fully loaded RV weighed to determine the correct tire pressure based on the tire manufacturer's weight/pressure charts. this will prolong the tire life and give your rig the best ride and handling. On hot days we have experienced the pressures on the tires rise 5 degrees F when traveling.
This is normal according to the tire experts. A tire monitoring system is a must to avoid rapidly changing tire conditions that may lead to a blowout. Also the system can monitor the tire pressures on a toad. a TPMS is a must for a MH IMHO.