tire pressure

Roger in VERMONT wrote:
We use 100 in front and 110 on rears. Have done this for 18 years this works best for us. We have a lot of weight 35,000 lbs to hold up.

And those pressures may be perfect for your coach, but 10-30 PSI off for the OP.

There IS NO ONE ANSWER FITS ALL. That is why the tire manufacturers go to the trouble and expense to develop and publish Inflation Tables (PSI for a given weight).

This is definitely one of those places where what is correct for one has no/little relationship to what is correct for another.

We use 100 in front and 110 on rears. Have done this for 18 years this works best for us. We have a lot of weight 35,000 lbs to hold up.

dodge guy wrote:
The 80 psi is for the RV at its full GVWR. My sticker states 90, but I’m under the GVWR by about 2k lbs. so I run mine at 86.
When my buddy got his he set the tires to 120 and always complained of the ride. I told him to set the tires to the placard. He said it handled and rode much better!

A slight rephrase and to correct some incorrect information elsewhere:

The tire pressure on the GVWR (Gross Vehicle Weight Rating) plaque is for:

Original size and load rating tires.

It is for PSI with each axle loaded to its GAWR (Gross Axle Weight Rating) which is also stated on the GVWR plaque.

Change tire sizes or load ratings, and you need to consult your new tire manufacturer for the correct PSI for your actual axle weights.


And, to expand on some of the earlier posts:

Best is to weight individual wheel positions with coach loaded as you go down the road, then, using the heavier wheel position on each axle, use your tire manufacturer's inflation table to determine the correct MINIMUM PSI. Adding 5-10 PSI, as long as it does not exceed the tire or wheel maximums is a good idea.

Next best is if you just have axle weights (vs individual wheel position weights). Here you will need to add a little more PSI as it is extremely unlikely that you have perfect left right weight distribution.

Next best is to go by the GVWR plaque. But (OK, large BUT), that assumes that your axles are not much above or below GAWR's.

Next best is to inflate to PSI on the sidewall of the tire. Again, this could be 30-40 PSI off from what your tire manufacturer recommends FOR YOUR ACTUAL WEIGHTS.

Lastly-- don't worry about it or let Bubba at the dealership just wing it (yes I am assuming Bubba is not clairvoyant and can not just look at your coach and tell what it weights). Please do not complain about ride handling or tire failures/blowouts if you use this one.

The 80 psi is for the RV at its full GVWR. My sticker states 90, but I’m under the GVWR by about 2k lbs. so I run mine at 86.
When my buddy got his he set the tires to 120 and always complained of the ride. I told him to set the tires to the placard. He said it handled and rode much better!

After reading numerous threads on this subject over the years I wonder how many people put this much effort into finding and maintaining the pressure in the tires on our cars, suvs and pickup trucks?

rk911 wrote:
the 120-psi on the tire is the maximum pressure the tires are rated for. and while you can inflate them to the max the result may be a very hard ride along with possible handling issues.

the 80-psi on your placard may be the optimal air pressure for the RV's weight when it left the factory or for the GVWR (gross vehicle weight rating) of the MH. using this air pressure will result in a much better ride but it still may be too low or too high for your MH's actual weight.

I would not overthink this. if the manufacturer specs 80-psi, go with 80-psi. Your handling will improve dramatically. Currently with your tires set at 100-psi, i'll bet the back end wanders all over the road and the handling is exhausting.

There are 3 pressures all but guaranteed to be wrong. IN the OP's case they are
80 PSI (The sticker) 120 PSI (The tires) and the pressure the tire store put in.

The proper pressure is kind of complex to figure out for many (Easy for me) but
You need wheel weights. Each wheel ideally (NOTE Duals are one wheel) Two ways to get this

Method one: A segmented scale. one axle per segment Total axle weight
Then pull on again but only one side on the scale NOTE this has to be a FLAT scale not a bridge type. Now you have weights on one end of the axle. subtract from total axle to get the other side.

Option two https://rvsafety.com/
Then click on the RV-Weighing tab on the right.

IN option 1 you download the tire inflatio chart from the tire manufacturer and work it out

In option 2 you tell them what tires you have, and they show up with the proper chart in hand. They figure it out for you and provide some basic education.

..
Why is proper inflation important?

Well if the pressure is too low then sidewalls flex excessively, over heat and BANG. if you do not know how to control a vehicle with sudden tire failure you are dead.. In any case major damage may happen.

You also have reduced control

IF over inflated the tire wears only in the center. the Ride is rougher and again there is loss of control

Proper inflation means the tire life is maximized and so is control.

chompchomp wrote:
I have an Itasca Sunova 35j, and posted on the driver's side of the coach it says 80 psi cold all tires. I have 6 19.5 Michelins and on the sidewall it's stamped 120 psi cold. I've always split the difference on the road. If we're at 100 psi all around, we're rolling.

I'm just curious how the rest of you navigate that; I mean 40 psi is a big discrepancy. Thanks for any feedback.

Are the tire sizes the same? I almost sounds like the original tires - the ones listed on the vehicle tire placard - were 235/85R16 Load Range E (80 psi max). If that is the case, then those 19.5's are probably an upgrade.

Oh and a Rule of Thumb: You don't want to get more than a 10% increase in pressure between cold and running. If you get more, then you need to slow down and think about getting tires with more load carrying capacity. (Maybe that's what happened here?)

If you get 15% or more, you need to take immediate action. Slow down AND get tires with more load capacity - within a week!

chompchomp wrote:
I have an Itasca Sunova 35j, and posted on the driver's side of the coach it says 80 psi cold all tires. I have 6 19.5 Michelins and on the sidewall it's stamped 120 psi cold. I've always split the difference on the road. If we're at 100 psi all around, we're rolling.

I'm just curious how the rest of you navigate that; I mean 40 psi is a big discrepency. Thanks for any feedback.

the 120-psi on the tire is the maximum pressure the tires are rated for. and while you can inflate them to the max the result may be a very hard ride along with possible handling issues.

the 80-psi on your placard may be the optimal air pressure for the RV's weight when it left the factory or for the GVWR (gross vehicle weight rating) of the MH. using this air pressure will result in a much better ride but it still may be too low or too high for your MH's actual weight.

the proper way to determine the correct pressure for each tire is to load the MH as you would for a trip and then take it to a certified scale to get weighed. loading includes full fuel, lp and fresh water tanks, food, clothing, supplies, pets, people and other stuff. individual corner weights are best but indiviidual axle weights will do. once you know the axle weights and have compared those weights to the published GAWR (gross axle weight rating) for your MH (to be certain neither axle is overweight) consult the Michelin tire inflation guide (available online). this will show the correct inflation for the weight you're carrying for the tires on that axle.

you can add any amount you like to the recommended pressure up to the tire's max. some folks add 5-10 PSI for peace of mind, some don't. you can add but you can't subtract, the rule is....inflate to the minimum pressure for the load being carried.

You need to weigh your rig with it loaded for the road then use chart for inflation level. I run my tires, not Michelins five pounds over the correct inflation chart for my tires.Michelin RV inflation chart