What PSI should my tires be at?

[ROBERT CROSS]

Originally Posted by Condo1

Hi, I have a 2019 28FT FC. The dealer inflated the tires to 80 PSI cold, the sticker on the trailer says 80 psi but I can tell you 80 PSI is not right. 80 Psi provides over 10K in load capability for a trailer that only weighs 7K loaded. I’ve put close to 30K miles on trailer and the center 1/3 of tires are shot.... 4/32 in... sure sign of overinflation.
I started checking my tires “hot” and the were all well over 80 PSI so I started reducing “hot” PSI to 75 psi which equated to about 65-68 PSI “cold”. Having new tires installed in May on way home from current trip. My new tires will be set at 65 PSI cold.

NEVER adjust psi HOT.
POI if checking OTR both tire & wheel should be cold, same goes for checking lug tightness.

Bob
🇺🇸

[Mollysdad]

What PSI should my tires be at?

Is this a trick question?

Originally Posted by gln826

Now I know why insurance rates are so high.

Oh, good, what tire pressure gets me the lowest rate?

Originally Posted by Peter417

Can you can explain to me why you don't run your TV tires at the max psi listed on the sidewall but you do run your trailer tires at the max PSI listed on the sidewall? Do you know what happens when you run your TV tires at the max PSI? Your tires are part of your suspension system. You can run a tire at very low PSI very slowly and you will have a nice soft ride. If you go to fast the sidewall heats up and you will have a blow out. My trailer tires are rated for nearly 4 times the weight of my trailer. So why would I need to run the same PSI as something 4 times as heavy?

My new hero!

Originally Posted by drbrick

Well I guess that tire manufacturers are completely stupid with their recommendations as are the vehicle manufacturers .. who on earth would possible follow what they recommend? After all they make them, test them and basically tell us this is the "best" PSI. So my truck tires are recommended at 35#PSI (BFGoodrich all-terrain TA KO2 lt275/65r20/e) and on our Airstream Goodyear recommends 65#PSI (GoodYear Endurance). I would be stupid to follow their advise and simply run at the MAX PSI on the side wall .. right? - after all, who do these manufactures think they are?

My point exactly!

Wait, you say GoodYear recommended 65 psi? How? Chart?

[1StreamDream]

I have also been trying to find definitive info from Goodyear, and I finally stumbled across the inflation table, showing max load at given PSI for the Endurance tires (table has several tire sizes). I don't see any specific recommendation for any given trailer, I think the only alternative is an individual seeking guidance has to start knowing the total weight on each tire. I think for me, I can only take the total trailer weight, divide by 4, then add some margin for unequal loading (left vs right or front axle vs rear axle). It seems to me that a 20% margin for safety/imbalance is more than adequate, and using that logic, for my trailer (7600 GVWR) I come the conclusion that 60 psi is plenty of tire pressure. If there are flaws in my logic/analysis, please help me understand where I am off base. My trailer has Goodyear Endurance ST225/75R15 load range E tires. Also, my "actual" weight from a CAT scale was more like 6200 but I am using GVWR of 7600 in the PSI planning.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

[Action]

Correct tire pressure is a Goldilocks thing.

There are negatives to being over filled or under filled.
The desired amount is to be just right.


Action

[davidz71]

I have a 1986 Airstream Sovereign and ran ST225-75-15 D rated tires at 60 psi rather than the max 65 on the sidewalk. It worked for me. After 12 years, yes 12 years on Maxxis M8008 tires, I had E rated Maxxis tires mounted on the same aluminum rims and run them the same pressure of 60 psi rather than the max 80 psi on the sidewalk. I haven't had any problems and it works for me.

[JCWDCW]

Rule of thumb is that tire pressure drops 1 pisg for every 10 deg F drop in temp. It works out pretty close on my TV. I don't check trailer pressures in winter storage!
All tire manufacturers state pressure is set at ambient temperatures. The pressure will rise as the tire heats up rolling down the road, and the Max tire pressure does include for increased rolling and ambient temperatures/pressure in the design of the tire.. So even if you run full 80 PSIG, a tire at that heats up to 110 deg F will only increase nominally 4 or 5 psig if ambient was 70 when pressure was set. That is well within the 10% over pressure that can be accommodated in the tire specifications.
Tire manufacturers don't recommend pressures for specific trailers. They do publish tables for specific loads on a specific tire model. We need to learn from experience how to tweak for best performance, but you can't go wrong with following the tire load tables if available. My experience as it seems others have also discovered is about 5 psig over load rated pressure works out about right. Better mileage, better tire life, and perfectly adequate braking.

JCW

[gypsydad]

It's like ground hog day with this thread!

[Mikebrady62]

Originally Posted by Trowbridge

I would like to politely disagree with others who recommend always using the Max PSI.
There is a reason it says "Max" and not "Best". That's because they are informing you of the maximum pressure for ongoing use in a wide range of temperature, weather and driving conditions. The tire manufacturer is telling you what is safe for that tire's extended use under a variety of loads. But tire pressure can (and should) be adjusted to fit your desired outcomes. For example, a rock hard tire inflated to max PSI will give your automobile great gas mileage. But it may not grip well or ride smoothly. And if you are driving on wet, icy, or snow-covered roads be prepared to meet the curb!

Per our local Cooper Tire dealer, you can adjust tire pressure down from the stated Max PSI to suite ride smoothness desired. But not dropping less than 15% to 25% below Max (note, varies by tire - classification, sidewall stiffness, etc.)..for obvious safety reasons. On our truck's 18" x 35" tires, we don't inflate them to the posted 80# PSI because (i) the ride is too stiff (it's a 3/4 Ton and I like my teeth); AND (ii) the tires balloon so that they are riding on a section narrower than the full tread width. Point (ii) causes the truck to veer a bit more because it's riding with less rubber on the ground. But with <60 LBS of air the truck rides smoothly and tracks great. But if we were carrying an extremely heavy load in the bed (or on a trailer) I might add more air.

You can look at your tires and play around with the air pressure. Look for when the outer edge of the tread is just touching the ground. If you've got the outer edges way off the ground I would suggest you've got too much pressure. Rubber off the ground doesn't help the trailer "stick" in a heavy braking situation (don't forget your trailer has brakes too) or (heaven forbid, an emergency swerve, etc.). Driving on snow or ice with max inflated tires greatly reduces their "sticktion" (my term) too. Finally, over inflated tires for your particular vehicle will wear out the tires in the middle first...because that's the only part getting wear. That will flatten out the tires very quickly.

For our trailer and its four tires, I run the tires 5 LBS less than posted sidewall max. (. All tread is touching. That's because the tires are inflated at the right level for our trailer (our 30' Airstream weighs just 4500# unloaded). That seems to keep the ride smooth and the trailer stopping nicely...even in rain or snow. And on our 1964 trailer , it's eliminated rivets shaking loose, doors opening, etc.

Final comment - What temperature is it outside the trailer? Is it 100 degrees plus or 50 degrees?. The air inside the tire will inflate the tire more just from driving (sidewall flex) and temperature counts. So that tire sitting at Max PSI when you start the trip in the mountains in early morning can be way above the safe limit when you are back down near sea level or driving across a desert.

Max does not always equal best! Thank you for your input!

[Mikebrady62]

Originally Posted by Action

Correct tire pressure is a Goldilocks thing.

There are negatives to being over filled or under filled.
The desired amount is to be just right.


Action

There are too many variables that go in making the right choice for you.
Going with Max Pressure all the time is not the right answer.

As Trowbridge stated before "There is a reason it says "Max" and not "Best"."

[Mollysdad]

Originally Posted by gypsydad

It's like ground hog day with this thread!

It's a curse.

Originally Posted by 1StreamDream

I have also been trying to find definitive info from Goodyear, and I finally stumbled across the inflation table, showing max load at given PSI for the Endurance tires I think for me, I can only take the total trailer weight, divide by 4, then add some margin for unequal loading (left vs right or front axle vs rear axle). Also, my "actual" weight from a CAT scale was more like 6200 but I am using GVWR of 7600 in the PSI planning.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

I'm a simple man. I like simple solutions, and so I believe Goodyear engineers took all factors into consideration when they made the chart. I don't need to apply another fudge factor.
Let's use your Cat scale weight. I can assume the tongue weight is not included since the trailer TIRES are weighed separately.
so, 6200 ÷ 4 = 1550
Your number 7600 ÷ 4 = 1900
according to the Goodyear chart, made by the experts,
weight of 1550 requires a minimum inflation pressure of 29 PSI.

You say, that's ridiculous, let's use your fudged number 7600, which one can see above gives us each tire carrying 1900 pounds. Consulting the chart, you could inflate to 42 PSI.
As a matter of fact, in order to arrive at 60 psi for 225/75-15 tires, you need to fudge that number all the way to 2380 x 4 or
9520 GVWR!!

Common sense tells us to stop reading the GoodYear chart. I did.


Okay, settled!

[Mike G]

Originally Posted by Peter417

Can you can explain to me why you don't run your TV tires at the max psi listed on the sidewall but you do run your trailer tires at the max PSI listed on the sidewall? Do you know what happens when you run your TV tires at the max PSI? Your tires are part of your suspension system. You can run a tire at very low PSI very slowly and you will have a nice soft ride. If you go to fast the sidewall heats up and you will have a blow out. My trailer tires are rated for nearly 4 times the weight of my trailer. So why would I need to run the same PSI as something 4 times as heavy? Please enlighten me with your insurance discount justifying smarts.

The recommended pressure for your trailer is on a placard stuck to the outside skin. (Or should be.) BUT, my placard says 80#, which is the tire's maximum recommended pressure. At 80#, cabinets pop open, vent covers fall off, and rivets can pop. If you look at the official load vs pressure tables for the tire, 80# is MASSIVE overkill. 60-65# is more than enough. I don't know why Airstream is doing this . . .

[Peter417]

Originally Posted by Mike G

The recommended pressure for your trailer is on a placard stuck to the outside skin. (Or should be.) BUT, my placard says 80#, which is the tire's maximum recommended pressure. At 80#, cabinets pop open, vent covers fall off, and rivets can pop. If you look at the official load vs pressure tables for the tire, 80# is MASSIVE overkill. 60-65# is more than enough. I don't know why Airstream is doing this . . .

I am not sure that's how things worked in 1966. Can someone confirm? If it did exist it is long gone on mine.

[ROBERT CROSS]

Originally Posted by Mikebrady62

"There is a reason it says "Max" and not "Best"."

"If you look at the official load vs pressure tables for the tire, 80# is MASSIVE overkill. 60-65# is more than enough. I don't know why Airstream is doing this . . .


But what if max IS best?
Again, statements that are meant to cover everyone.

POI..We ran GYM's for 11 seasons at the 'MAX' sidewall pressure of 65 without a failure. Or any AS damage.

Bob
🇺🇸

[1StreamDream]

Originally Posted by Mollysdad

It's a curse.

I'm a simple man. I like simple solutions, and so I believe Goodyear engineers took all factors into consideration when they made the chart. I don't need to apply another fudge factor.
Let's use your Cat scale weight. I can assume the tongue weight is not included since the trailer TIRES are weighed separately.
so, 6200 ÷ 4 = 1550
Your number 7600 ÷ 4 = 1900
according to the Goodyear chart, made by the experts,
weight of 1550 requires a minimum inflation pressure of 29 PSI.

You say, that's ridiculous, let's use your fudged number 7600, which one can see above gives us each tire carrying 1900 pounds. Consulting the chart, you could inflate to 42 PSI.
As a matter of fact, in order to arrive at 60 psi for 225/75-15 tires, you need to fudge that number all the way to 2380 x 4 or
9520 GVWR!!

Common sense tells us to stop reading the GoodYear chart. I did.


Okay, settled!

I hear you, I like to keep things simple myself, but I'm not sure what you are getting at. My "fudge" factor is to account for an unequal balance from one tire, or axle, to the next. I won't go to the CAT scale every time I load my trailer, and I don't think the CAT scale gives me weight breakdown that precise, so for my own piece of mind, I add the "fudge" factor. I agree with you that Goodyear accounts for all aspects when they publish that chart, but the chart is also for an individual tire, not a group of tires, so taking the total weight divided by 4 is the ideal balance, and will vary across trailers and individual packing methods, I don't think I will get that ideal balance each time I prepare for a trip. Airstreams are well balanced by design, as I am learning, so Airstream trailers are probably safer in that respect than other trailers, but I still think there can be some variance in the balance. Maybe I'm close (to ideal balance), and maybe closer than I think, but thats why I feel like I want a little margin in my plan. Also acknowledge my "fudge" factor might be a ridiculous extreme, but I don't have other actual data for my trailer so I just went with GVWR + 20%. I also agree with you about your other point, when the chart says 29 PSI is enough, then I am not a fan of that plan. I don't think I'm going below 60 psi, but I like the dialog about all these factors, it helps an apprentice like me get a little more educated. Thanks for the perspective, appreciate the insights.

[Mollysdad]

Originally Posted by 1StreamDream

I hear you, I like to keep things simple myself, but I'm not sure what you are getting at. My "fudge" factor is to account for an unequal balance from one tire, or axle, to the next.

Don't take offense. I say "fudge factor" because that's what we always called it in math and physics. Scientists would call it "K" or even "dark matter".
I'd like to think the designers of RV's took the weights of all the interior sections into account and then put the shower opposite the fridge. I hope my tire weights are close, but like you I've never weighed each wheel.
I attended a rally long ago (not AS) and we were given the option to have each tire weighed. We simply stopped, the group placed a thin scale in front of each tire, I drove up on them, paid my $25 and they e-mailed me the results. I was confident in my tire pressure then.
I'd love to see an AS rally do that, perhaps at Alumalina?
https://www.rvsafety.com/rvweighing

[robertwarren]

We run our Goodyear Endurance tires at 65psi. Full timing for 3-years has taught us that the Max tire pressure bounces the contents of our 2018 27’ Airstream FC too hard and affects my towing control. We also tow at 65 mph max.

[jadatis]

I began reading every post, to see if you gave more tire info, but stopped after first 8.

Read your own post #8 about P tires and ST, with 3300 lbs total weight , but in opening post you write 2800 lbs.

If you now give total weight, or best weighed, and the tire specifications, This Peter will trow it in his made calculator, in wich formula used that leads to higher pressure then the official european one, wich on its turn gives higher pressure then officially used american formula.
Then I first add 11% to the total weight minus 10% towbar weight, for max reserve without bumping( so also on LT and ST , and not only for P-tires)

Then probably my calc comes to even lower pressure then your 40/45 psi mentioned.
I estimate that because of the low total weight and pretty oversised tires.

But first give me the data.
From tires
1 . Maximum load or loadindex
2. Kind of tire( ST , LT, P-), and loadrange
3. Speedcode.

[Peter417]

Originally Posted by jadatis

I began reading every post, to see if you gave more tire info, but stopped after first 8.

Read your own post #8 about P tires and ST, with 3300 lbs total weight , but in opening post you write 2800 lbs.

If you now give total weight, or best weighed, and the tire specifications, This Peter will trow it in his made calculator, in wich formula used that leads to higher pressure then the official european one, wich on its turn gives higher pressure then officially used american formula.
Then I first add 11% to the total weight minus 10% towbar weight, for max reserve without bumping( so also on LT and ST , and not only for P-tires)

Then probably my calc comes to even lower pressure then your 40/45 psi mentioned.
I estimate that because of the low total weight and pretty oversised tires.

But first give me the data.
From tires
1 . Maximum load or loadindex
2. Kind of tire( ST , LT, P-), and loadrange
3. Speedcode.

Sorry for the confusion. Post 8 is not my tires. That is a quote from the website.

[jadatis]

About chalk test.

Put a line of chalk from side to side, and drive a qarter of a mile.
Then if sides are worn and centre still stands, tires to soft.
If middle wears of , tires to hard.

Now a radial tire stays in a large range with total width on the ground. It has to be much to high psi, before only riding on centre of tire.
And even to low psi can still wear the chalk evenly.

So to be short, verry unreliable method.
If you want to use it safe, begin with much to high psi( but wht is much to high), and spop lowering the pressure when the chalkline wears even.

[Bill M.]

I have been a serious puller of a trailer for 12 years and reader of the forums. My 1988 trailer says load range C bias ply tires at 43 psi on the placard. It is hard for me to believe that I ought to be running a tire with 80 psi in it now.

My understanding is that the famous load/pressure chart is just a chart of deflection. That is, all the pressures and loads on the chart give the same deflection and that deflection is the maximum deflection the engineers want. Deflection has to be highly dependent upon pressure and not much on type of tire. So I doubt if they make a chart for each style tire.

There did not seem to be much of a problem deciding inflation until Goodyear came out with the load range E endurance tires. Previously the load range D tires at full inflation pressure of 65 seems about right for most Airstreams as a max inflation.

I am currently running a P XL tire at 48 psi. It is time to buy tires again. Again I have to wade through all this and decide. My trailer rides smooth. It tracks well. I do feel a slight pull from trucks. I feel more of that pull if I tighten the WD too much. In 3 sets of these tires in 13 years the tires do not fail from "interplay shear" nor do they pop off the rims when backing.

Whatever, I just do not see 80 psi in my near future. I pumped my rear truck tires up to that once. But very soon let them back to the placard recommended 70 psi.

There was an "old school" theory that you should not run heavy duty tires (load range D and E) at lower pressures because they would heat from the deflection. Maybe with the radial designs that is no longer a consideration. I notice that Goodyear does make a D rated endurance in a slightly smaller size. But I have not seen anybody mention that they have installed them. Is anybody running a set of them?