What tire pressure to fill tires to?

[Sdalton291]

Yes, a dumb question, but trying to take care of an inherited motor home. 38’ Mountainaire. Tires say max 110 psi, so what is ideal pressure to fill these to?

 

[8Muddypaws]

There isn’t a simple answer. The ‘right’ way to figure this out is to take the coach to a truck scale and have it weighed, preferable each of the four corners independently but front & back is more common.

Then consult the tire manufacturers air pressure/weight tables and adjust the pressure accordingly.

Poor man’s alternative: find the weight sticker somewhere in or on the coach. It will show the factory weight estimates.

 

[Mark_K5LXP]

If you need to move it before you have a weight, the placard gets you there. Barring those more is better than less so max sidewall would be OK until you do know. Something else to know about a new to you rig is how old the tires are. Check the DOT date on the sidewall.

Mark B.
Albuquerque, NM

 

[Utclmjmpr]

The pressure listed on the tire is the maximum pressure at the maximum weight on the tire,,Your coach will probably not weigh that much so the loaded weight of the coach should be established..>>>Dan

 

[LarsMac]

I would suggest generally around 5 to 10% below the MAX on the tire. At max inflation, you'll find it a bit uncomfortable. That depends in the weight of your vehicle, too.
More importantly you want the pressure to be as close to equal on all tires of each axle as possible.

 

[Larry N.]

Once you've determined the weight on each axle (or better yet, each wheel) you can then use the tables in the link, going down the left column to your tire size, then across to your weight on that axle (wheel)- keep in mind that all tires on an axle should be the same pressure, and you need to check that you're looking at the field for duals or not duals, depending on what's on that axle:

https://swcompanies.net/wp-content/uploads/2019/08/Tire-Load-Inflation-Table.pdf

 

[John From Detroit]

As others have said the only way to be correct is to load it up for a trip and drive it to the scales.
Or call Aweigh We Go (RV safety folks... RVSEF Home ) and use the RV Weighing drop down)

This gets you the ideal pressure for each tire or pair of tires. (Duals)

It's how I did it. for your tires 100-110 to the weigh station/site (Aweigh we go comes to you with portable scales)

 

[Kirk]

And while you are checking the tires, check the date that each tire was constructed and if more than 7 years old, you would be wise to replace them ASAP.

 

[TheBar]

Whoever you inherited it from likely accumulated unneeded junk. So before weighing it purge all the excess weight you don't need. Less is always better. But do fill your gas tank and any drinks, food, and clothes you will be taking on a trip. If you plan on boondocking you might want to fill your fresh water tank.

Some people carry enough tools to setup a master mechanic's shop. You only need the essential tools you might need on the side of the highway. If you can drive it to the next town you can buy specialty tools there.

Some people carry every kind of glassware, plates, bowls, and cooking appliance known to man. Charcoal grills, electric grills, crock pots, instant pots, dutch ovens, etc. Get real. Are you really going to be fixing 7 course dinners or grilling hot dogs and hamburgers over the fire?

 

[CharlesinGA]

There should be a placard near the drivers area with chassis GVWR, max axle weights, tire sizes and pressures, etc. Those pressures will be based on the specified tire size and the chassis at max weight, so they are a good starting point. You won't go wrong using those pressures. Weigh it and find tire pressure tables for your size tires and you will get closer to the "right" pressure.

Charles

 

[RayIN]

Yes, a dumb question, but trying to take care of an inherited motor home. 38’ Mountainaire. Tires say max 110 psi, so what is ideal pressure to fill these to?

Sorry, I duplicated Charles reply.
You should find a Federal tire placard near the drivers area that lists tire pressure for a loaded to its GVWRl. That is the tire pressure for the fully-loaded MH.

 

[Derby6]

Yea I like the last 2 reply's. Not that the earlier replies are wrong in any way, but IMO overcomplicating air tire pressure for a stock vehicle.

 

[Larry N.]

Yea I like the last 2 reply's. Not that the earlier replies are wrong in any way, but IMO overcomplicating air tire pressure for a stock vehicle.

Ahh, but 5-10 psi (say 90 down to 80) can make a HUGE difference in handling. Those are the differences for me on the 2010 Bounder I bought. The dealer had put 90 psi in the front tires, and there were a few spots on an Interstate where the bumps nearly made me lose control, nearly lifting the front end off the ground at 60-65 mph.

After taking the advice to use the tire pressure tables vs actual weight, where I found that the proper inflation was 80 psi, those bumps no longer gave me any problems. The coach also rode better and had less tendency to follow tire-worn grooves in the highway.

So I'm BIIIG believer in proper pressure. BTW, a similar pressure difference (different figures though) on my Newmar Ventana (120 psi vs 105 psi) didn't make quite as drastic a difference (air ride is great) but still took away the wandering back and forth in those tire-worn grooves in the highway and gave a slightly better ride.

I'm a believer!.........................................

 

[Gary RV_Wizard]

Poor man’s alternative: find the weight sticker somewhere in or on the coach. It will show the factory weight estimates.

It's not "somewhere". The federal-required Tire Placard will be on the interior sidewall by the driver seat. It will show the coach builder's recommended tire pressures, which are almost always the pressure needed to support a fully-loaded coach, i.e. the actual loaded weight is at the GVWR. That's overkill if the coach is very lightly loaded, but it's safe.

 

[8Muddypaws]

Funny thing. I have one on the inside of a kitchen cabinet. And another behind the drivers seat on the wall.

 

[Gary RV_Wizard]

Funny thing. I have one on the inside of a kitchen cabinet. And another behind the drivers seat on the wall.

The RVIA used to require their standard weight-capacity label to be placed in a cabinet, either kitchen or above the driver seat, but when the feds set a new standard for both tire & weight placards, they specified the driver seat sidewall for motorhomes (trailers are different). Fleetwood did both places for a number of years.

 

[8Muddypaws]

That’s why you’re the wizard Gary.

 

[Gary RV_Wizard]

Just been around a looong time.

 

[Mr Lars]

Whoever you inherited it from likely accumulated unneeded junk. So before weighing it purge all the excess weight you don't need. Less is always better. But do fill your gas tank and any drinks, food, and clothes you will be taking on a trip. If you plan on boondocking you might want to fill your fresh water tank.

Some people carry enough tools to setup a master mechanic's shop. You only need the essential tools you might need on the side of the highway. If you can drive it to the next town you can buy specialty tools there.

Some people carry every kind of glassware, plates, bowls, and cooking appliance known to man. Charcoal grills, electric grills, crock pots, instant pots, dutch ovens, etc. Get real. Are you really going to be fixing 7 course dinners or grilling hot dogs and hamburgers over the fire?

Good Heavens, you must know my Wife!! Anytime she mentions ‘going somewhere’ with the RV, its like ‘moving day’.

 

[Gary RV_Wizard]

Some people carry every kind of glassware, plates, bowls, and cooking appliance known to man. Charcoal grills, electric grills, crock pots, instant pots, dutch ovens, etc. Get real. Are you really going to be fixing 7 course dinners or grilling hot dogs and hamburgers over the fire?

Just different strokes. Some people travel in loftier circles than others. And if you spend several months in the RV, visiting friends or attending big rallys, there will be more occasions where cooking a full meal or using plates & stem wear is more suitable than grilling hot dogs.

That said, it's wise to balance the social niceties with some concern for the available space & weight.