Correct Tire Pressure

[apopj]

Hello all,

I am having a heck of a time trying to find the correct tire pressure for my 2001 30 foot Holiday Rambler "Admiral". The tire size is 220/70R19.5. I have read and re-read the manual and it talks about if the weight here is... then the pressure here is... however, if the pressure here is... then the pressure here is.... Eggggghhh.......

SO, can anyone give me a ball park figure of where to start? This would be an unladen coach, empty of water with half tank of fuel. The tire says 110 pounds, but the front end feels like there are no springs or shocks at that pressure. I have it at 95 and still am taking a beating going down anything but a newly paved asphalt highway.

Any help would be appreciated. Once I get the unit loaded, I will go to the scales and weigh the corners/front and rear/ and total. But for now, I need help to save the chassis from being destroyed by bumps. Oh, I have the Triton V10 Engine if that matters......

Thanks again, Jeff "We're Houseless NOT Homeless"

[DanKathyC]

lots of motorhomes- maybe all of them -have a sticker on the wall beside the drivers chair that lists among other things the tire size and pressures. these pressures will safely carry the maximum axle weights when in the proper tire. my opinion is that 19.5s cannot be made to ride good. less bad is better

[wildtoad]

Similar to above, look for the placard and barring any other information use the pressure stated. You could also take your GAWR’s and look the weights up in the tire chart for your manufacturer and tire size. The very LAST pressure you will want to use is what’s on the tire.

[jomo]

Originally Posted by DanKathyC

lots of motorhomes- maybe all of them -have a sticker on the wall beside the drivers chair that lists among other things the tire size and pressures. these pressures will safely carry the maximum axle weights when in the proper tire. my opinion is that 19.5s cannot be made to ride good. less bad is better

Dang... how did we ever make it when most were 16's

[LVJ58]

The 245/70R19.5's on our 38' coach calls for a minimum of 80 psi. On yours I would think that 70 to 75psi would be more than adequate.

Good luck and safe travels....

[TeJay]

When we bought our coach 2014 unit on 2013 chassis with the GY 19.5" tires/rims I started experimenting with the air pressures and did so for about 6 months. Finally settled on about 82 to 84 lbs. Then I looked on the sticker and yep it said 82 lbs was recommended.

The manufacturers sticker is always a good place to start.

[dbaer70]

I run 85 psi front/ 87 rear this should put you in the ballpark. We have a 31' Vista. Don Baer

[scbwr]

From what I read in the lengthy tire pressure posts, and being new to a class a motorhome, I took my motorhome to the CAT scales (motorhome loaded with most of our gear, full tanks gas, water and propane) and got the axle weights. Since I couldn't get a weight for each individual tire, I added 10% to the weight of each axle and then used the inflation chart for the Toyo tires (Toyo M154 245/70R/19.5) I just had installed. Based upon those weights, it indicated 85 lb/psi for the front tires and 95 lb/psi for the rear tires. After talking to the technician that did a front end alignment, in which he talked about weight shifting to the front axle when braking, descending mountains etc. I may increase the front pressure to 90 lb/psi.

https://www.toyotires.com/media/2155...ion_tables.pdf

one link for tire pressure discussion

http://www.irv2.com/forums/f258/just...ml#post3850777

[Waiter21]

Scbwr;

Exactly. REMEMBER - The pressure from the table is the MINIMUM pressure for that weight, measured cold.. You can go with higher pressure, just don't exceed the maximum weight / pressure thats listed on the tire.

There's usually a placard or paper near the drivers seat (inside a cabinet or wall) that shows the manufactures recommended pressure.

[scbwr]

Originally Posted by Waiter21

Scbwr;

Exactly. REMEMBER - The pressure from the table is the MINIMUM pressure for that weight, measured cold.. You can go with higher pressure, just don't exceed the maximum weight / pressure thats listed on the tire.

There's usually a placard or paper near the drivers seat (inside a cabinet or wall) that shows the manufactures recommended pressure.

Agreed! The Newmar's recommended pressure is 93 lbs./psi and I assume that would be for a motorhome with maximum cargo capacity. According to my weights, I was close to 1,000 lbs. below maximum weight. And, I can only see us adding two to three hundred pounds of weight for a very long trip and I usually only carry about 1/3 of a tank of fresh water which would be considerably lighter than a full tank.

Also, when I followed the 85 lb. and 95 lb. guidelines, those pressures allowed for more weight than I actually calculated which was increased by 10% of the actual weight. At some point, I hope to be near a place that can do a weight check for each wheel to see if one side of the motorhome is much heavier than the other. That's another reason why I will bump the front tires to 90 which will only be slightly less than the 93 recommended by Newmar.

[Russ Silber]

Originally Posted by apopj

Hello all,

I am having a heck of a time trying to find the correct tire pressure for my 2001 30 foot Holiday Rambler "Admiral". The tire size is 220/70R19.5. I have read and re-read the manual and it talks about if the weight here is... then the pressure here is... however, if the pressure here is... then the pressure here is.... Eggggghhh.......

SO, can anyone give me a ball park figure of where to start? This would be an unladen coach, empty of water with half tank of fuel. The tire says 110 pounds, but the front end feels like there are no springs or shocks at that pressure. I have it at 95 and still am taking a beating going down anything but a newly paved asphalt highway.

Any help would be appreciated. Once I get the unit loaded, I will go to the scales and weigh the corners/front and rear/ and total. But for now, I need help to save the chassis from being destroyed by bumps. Oh, I have the Triton V10 Engine if that matters......

Thanks again, Jeff "We're Houseless NOT Homeless"

Use 80lbs in all tires. Mine is 1999 Gas Dutchstar. Even loaded for travel with full gas 1/4 water and foof and clothing for 2 and 3 dogs etc. Ride is fine on most roads. Tolerable on really bad stretches of highway. Have 66000 on F53.[emoji12]

[bucks2]

Stop. Think about the real world. What brand tires do you have? Are they the original tires that the factory put on? Or are they replacements? Who do you suppose does the most research on Brand XYZ tires and what pressures work best with which weight? Would that be the factory that had trouble finding 10 screws that matched to screw the window trim on or the folks that make the tire and warranty it? Do you suppose the factory designed your rig for a particular tire brand and model? Or do you suppose they put on low bid when they built it?

Find the exact brand and model tire you have. Go onto the tire manufacturers web site and print off their load table. For X weight on single use XX PSI. For X weight of duals use XX PSI. That's the pressure you want to use. The tire does not care what brand MH you have, it only knows it's on the rim and it has X weight and it goes round and round.

Next, because you don't know how much you coach currently weighs you need to make an educated guess until you get to a scale. Axle weight is good, 4 corner weight is better but much harder to get. There are a hundred posts about putting one side on the scale and all that so I won't get into that here. Find out what your coach's dry weight is, probably from the manual. Add some for full tanks, etc. Then add 5-10% for a fudge factor. You want to over guess your weight, not under guess.

Use a good digital air pressure gauge. Use the same exact gauge every time. Watch your tire wear. If it's not nice even wear, fix the problem. Obvious things are if both outside shoulders are wearing, the tire is underinflated. If the middle is wearing the tire is over inflated. If only one shoulder is wearing then worn front end parts or alignment is out.

If the air pressure is right for the weight it's carrying then your tires will take you safely there and back. The rough ride can be from a variety of things, shocks, tires with too much capacity, (16 ply rated sidewalls on a lightweight utility trailer would be an overkill example.) poor MH construction, etc.