Tire pressure for 275/80R22.5 LR H tires

[mikestock]

I'm sure this has been a topic many times in the Class A forum. I have been searching for quite some time but can't find a recommendation, even in the manual. Running 6-275/80R22.5 load range H tires and know the max psi recommendation is 120 psi. I am coming from a heavy 37' fiver with load range E tires and always ran them at the 80 psi max.

I just purchased 6 new Continental tires and the installer recommended running them at the max, 120 psi, but this guy has more experience with commercial trucks than RV's. They are mounted on a 40' Phaeton with no unusual loading. I had them set at 105 psi but would like some input from others with experience in load range H tires.

[mikestock]

One last thing to add. The person I bought the coach from told me he kept the pressure at 100 psi. The results of this was 26,000 miles with the Goodyear tires showing no obvious signs of unusual wear or defects. He did say that he once had a flat due to a nail. I saw the boot patch where it was repaired when the old tire was removed. The treads looked, to me, like they do on the new tires I bought. I only replaced the tires due to the age.

[DSDP_Don]

"mikestock".....Weighing all four corners of your coach can be a difficult thing to do. It's hard to find someone who can do this. Better than nothing, is to way the front and rear separately. Most truck stops will do that for you, many even for free. I think the most I've ever paid is $7.00.

For right now, 110 psi sounds good until you get it weighed. I weighed my coach a year ago when I bought it new and after it was loaded. The weight charts said I could run about 105 - 110 psi. I was looking for a quality ride, so I started at the 105 setting. It was too low, over the last year, I've bumped them to 112 through trial and error. Last month, I converted to all electric and removed my propane tank (350 pounds) from just behind the driver's wheel. I checked my tires and at 12K miles, my left front was showing some under inflation wear compared to my right front. I attributed this to the propane tank and full wall slide on the driver's side. It would have been nice to have an individual wheel weight, but I haven't found anyone locally to do it. So with the removal of the tank, I adjusted the air to 115 psi and will see how that works. I know it will make my ride a little harsher, but I expect that my air pressure is dialed in for what is right for the coach.

The moral of this long winded post is that there are several factors when it comes to the front tires that you need to watch and may spend some time adjusting before you get it right. The minimum though, is to get that front end weighed.

[tropical36]

keepingthelightson wrote:

tropical36 wrote:

keepingthelightson wrote:
I have Yokohama 16 ply tires on my Phaeton and I run 100psi in all six. Weight is a factor as others have mentioned. When I replaced my old ones the truck tire shop told me to run at 100psi. Nice ride and I am very pleased.

Good luck;)

So, what you're actually saying is that you have no idea as to whether you're running on tires that are under inflated or over inflated and please correct me if I'm wrong here? I mean this truck shop could have got the coach weighed, I guess.
Now, if I was to go with a number and rather pull one out of a hat, I would look at the rig's GVWR for each axle and use the tire inflation chart to coincide with that number, then add a little cushion, as previously said. Having said that, you could be under or over the gross weight and I for one, like having some idea as to which. Also knowing the total GVWR helps when determining the allowable toad weight by subtracting that number from the GCWR. I guess I just like knowing things, is all and am a curious sort of person, anyway.

Never said I had NO IDEA! I said the psi is fine for my application. There's one in every bunch. Go piss on some other fire. :E

No need to get huffy and didn't think I'd hit a sore spot that easily with actually trying to help some other readers here. Knowing whether or not you're overinflated or under inflated could turn out to having some importance with a lot of RV owners who frequent these threads, you know.

[keepingthelight]

tropical36 wrote:

keepingthelightson wrote:
I have Yokohama 16 ply tires on my Phaeton and I run 100psi in all six. Weight is a factor as others have mentioned. When I replaced my old ones the truck tire shop told me to run at 100psi. Nice ride and I am very pleased.

Good luck;)

So, what you're actually saying is that you have no idea as to whether you're running on tires that are under inflated or over inflated and please correct me if I'm wrong here? I mean this truck shop could have got the coach weighed, I guess.
Now, if I was to go with a number and rather pull one out of a hat, I would look at the rig's GVWR for each axle and use the tire inflation chart to coincide with that number, then add a little cushion, as previously said. Having said that, you could be under or over the gross weight and I for one, like having some idea as to which. Also knowing the total GVWR helps when determining the allowable toad weight by subtracting that number from the GCWR. I guess I just like knowing things, is all and am a curious sort of person, anyway.

Never said I had NO IDEA! I said the psi is fine for my application. There's one in every bunch. Go piss on some other fire. :E

[tropical36]

horizon36 wrote:
The only to correctly determine tire pressure is to weigh each wheel position individually. Weighing the axle won't tell you if you are out of balance and if you split the reading and inflate accordingly you might have one tire under-inflated. This can lead to a blow out.

In the mean time look at the federal data plate near the driver seat and it will tell you what to inflate the tires to. This is determined by the gross axle weight ratings and the tire manufacturers inflation charts for that weight. Don't guess as this is a critical safety factor. Here's a link to a website where you can learn more. RV WEIGH - Mobile Weigh Station

This is one of the changing variables for adding a 10 - 15psi cushion, as the weight can be more so on one side or the other and change too, when you decide to bring along your heavy duty BIL and he's likes riding in the passenger seat or at the dinette all the time. Also going from Death Valley up to Yosemite NP can lower the psi with lower ambient temps. Now we have a situation where there's a slow leak that might take a full 24hrs to detect. I don't mind checking tire pressures each day before getting underway, but certainly am not going to be changing the psi in the tires every time we change course. As for what's on the Federal RV sticker, mine says 65psi for 1998 and don't even know of a tire inflation chart that goes that low nowadays, so that's my story and I'm sticking to it... 🙂

[mikestock]

Thanks all.
I guess I'll stick with 110 psi until I get a chance to get a weight. The max is 120 psi for load range H and for my wheel hubs. I may make adjustments after weighing but will allow for about 5 to 10 psi above the calculated minimum.

[horizon36]

The only to correctly determine tire pressure is to weigh each wheel position individually. Weighing the axle won't tell you if you are out of balance and if you split the reading and inflate accordingly you might have one tire under-inflated. This can lead to a blow out.

In the mean time look at the federal data plate near the driver seat and it will tell you what to inflate the tires to. This is determined by the gross axle weight ratings and the tire manufacturers inflation charts for that weight. Don't guess as this is a critical safety factor. Here's a link to a website where you can learn more. RV WEIGH - Mobile Weigh Station

[tropical36]

keepingthelightson wrote:
I have Yokohama 16 ply tires on my Phaeton and I run 100psi in all six. Weight is a factor as others have mentioned. When I replaced my old ones the truck tire shop told me to run at 100psi. Nice ride and I am very pleased.

Good luck;)

So, what you're actually saying is that you have no idea as to whether you're running on tires that are under inflated or over inflated and please correct me if I'm wrong here? I mean this truck shop could have got the coach weighed, I guess.
Now, if I was to go with a number and rather pull one out of a hat, I would look at the rig's GVWR for each axle and use the tire inflation chart to coincide with that number, then add a little cushion, as previously said. Having said that, you could be under or over the gross weight and I for one, like having some idea as to which. Also knowing the total GVWR helps when determining the allowable toad weight by subtracting that number from the GCWR. I guess I just like knowing things, is all and am a curious sort of person, anyway.

[keepingthelight]

I have Yokohama 16 ply tires on my Phaeton and I run 100psi in all six. Weight is a factor as others have mentioned. When I replaced my old ones the truck tire shop told me to run at 100psi. Nice ride and I am very pleased.

Good luck;)

[Vulcan_Rider]

tropical36 wrote:

As said over and over again, at least weigh each axle and use the tire inflation chart for your size.

And as I have said before (not often 'cause I'm new here) all of that should ***NOT*** be necessary if everything is still stock.....or better in the case of tire ratings.

In that case, you should be perfectly fine with the original recommendations. Finding out what that is should be much easier that finding a truck scale.

If you are OCD or a little paranoid, then by all means get each axle weighed and check the charts. Any place with scales for semi trailers should be able to do it.

Your point about "upgrading" the tires without considering the wheels too is an excellent one. You actually could be doing more harm than good.

[tropical36]

mikestock wrote:
I'm sure this has been a topic many times in the Class A forum. I have been searching for quite some time but can't find a recommendation, even in the manual. Running 6-275/80R22.5 load range H tires and know the max psi recommendation is 120 psi. I am coming from a heavy 37' fiver with load range E tires and always ran them at the 80 psi max.

I just purchased 6 new Continental tires and the installer recommended running them at the max, 120 psi, but this guy has more experience with commercial trucks than RV's. They are mounted on a 40' Phaeton with no unusual loading. I had them set at 105 psi but would like some input from others with experience in load range H tires.

As said over and over again, at least weigh each axle and use the tire inflation chart for your size. I always add 15 - 20psi for all the variables and can't see how one could remain anywhere near correct throughout their trip without doing so.
Having said that and as an added note, modern tires on some of these older coaches have a max psi rating that far exceeds the wheel rim max and would consider that dangerous, pumping them up to max. and above the wheel psi rating.

[Vulcan_Rider]

Every vehicle made for the US market since about 1970 is supposed to have a sticker or placard somewhere with the recommended tires and pressures.

Look:
Inside all the door jams.
Inside the glove box or other storage areas around the cab.
If you do end up contacting the manufacturer, also ask them where the card is supposed to be.

Just because you upgrade the load range of the tires (this may not apply to you), that doesn't necessarily mean that you need to up the air pressure.....at least not much.

[walker760]

Have a 2006 40QSH Phaeton and the owners manual says to keep the pressure at 110 LBS. Michlin tires... Hope this helps

[wolfe10]

Absolute best answer is to weight it and use Continental's inflation table to determine the minimum acceptable PSI for your load. Perhaps add a little as a fudge factor.

But, until then, IF (big IF) this is the OE size, you can look at your GVWR sticker to determine the correct PSI assuming all axles are loaded to their GAWR.

Sure hope that is over-inflated, but sure safer than under-inflated.