tire psi

[jimcatinmi]

good morning, I just switched from a tt to a 5th wheel and I noticed when hooked up my tires look a little low. Should I set the psi to what the tire says or what's on the door?

[coolbreeze01]

Tires with a higher ply rating can hold more air and can carry more weight.

Low psi causes heat and heat kills tires.

[Groover]

I can tell you from experience that if you ask either the vehicle manufacturer or the tire manufacturer they will tell you to go with what is on the door. Personally, I would go 5 to 10 PSI over what is on the door since tires only leak down and not up, no pressure guage is exact and it seems to be a lot less damaging to have too much pressure than not enough. Since the vast majority of LT tires on the market are Load Range E I am guessing that is what is on your truck and they are rated for 80psi. I would not fill them past 50 PSI under any circumstances. All it will do is make your ride rougher and possibly destabilize the vehicle that was designed to run softer tires. If you are old enough to remember the Ford Explorer/Firestone debacle it was demonstrated that if you ignored the factory rating and filled the tires to their rated pressure the Explorer became unstable and much more likely to roll.

If the truck had been equipped with LT tires from the factory the door sticker would call for 36psi and the max on the LR C tires that came on the truck would be 51psi.

I am running a similar tongue weight to what you expect to have and find that 45psi seems to work well.

[Grit_dog]

time2roll wrote:
Truck... I would add up to 10 psi to the rear tires and 5 psi to the front, not to exceed the sidewall max.

Pretty broad and probably inaccurate statement, unless you have ESP and can see the guy's tires and door sticker through your computer screen.

[BenK]

TV door tire label mainly has OEM information for a stock tire/wheel

Most has ‘ride quality’ PSI recommendations and few has towing recommendations. That is usually in the manual and if towing heavy, use the tire sidewall PSI info (which is the max weight & PSI)

All wheels have a max weight and max PSI for that weight carry rating. Ditto info molded into the tire sidewall...both max weight carry and max PSI. Along with other info, like speed rating and class of tire

Whether wheels have a weight rating and PSI rating is an almost forever discussion with no resolution...ever

But this has helped folks understand this and use the old adage of “a chain is only as strong as its weakest link”...

In this case, look at the tire valve that your wheel has

Tire valves also have ratings to go along with the class of tire and wheel rating

I only use 200 PSI tire valves for my class “LT” tires and notice that there are many valve stems rated much lower in PSI...ditto wheels...they have PSI ratings too

So many folks have no clue and just assume the tire shop has installed the correct valve stem on their ‘up grade in class’ tires...sorry, too many tire shops will...nor understand that they have a rating

Here is a good site explaining valve stems matched to tire/wheel ratings

eTrailer, Can I Determine the psi Rating of a Wheel
Posting from iPad is wacky and links most times will not work with a hot link, so here is the link = https://www.etrailer.com/question-230756.html

eTrailer wrote:

Can I Determine the psi Rating of a Wheel

Question:
I have Goodyear G614 tires ST235/85/R16 with a 110 lb pressure . How do I determine if my steel rims are capable of handling thus pressure?
asked by: Jeff C
Helpful Expert Reply:
Since wheels will be able to withstand the psi rating of any of the tires that are meant to fit it you will need to look at the valve stem as that is the deciding factor.

If your valve stem has the rubber all the way up to the threads, like part # AM20903, then it will be rated around 65 psi. If there is some reinforcement between the rubber and the threads, like part # AM20904 or # AM20907, then your valve stem can be rated between 80 and 100 psi. The only valve stems that are rated for more than 100 psi are metal ones like part # AM20906. If your wheels do not have metal valve stems then they will not be able to hold the pressure of 110 psi that you require.

Ultimately unless you bought the wheel from us and can give me the part number then the best way to know what the psi rating of your wheel (or valve stem rather) is would be to call the manufacturer.

helpful expert reply by: Jon G
Jon G

Do disagree on one point...wheels also have weight and PSI ratings

Personally saw and fixed a trailer wheel back in the late 60’s working my way through college (mechanic, welder, tire monkey, etc)

A guy came in saying his trailer tire would NOT keep pressure and had gone to several tire shops. We were a full service shop, from commercial to racing. Shop owner wouldn’t let me work in the last two bays, because they were for commercial and split rims were the norm

Took that tire/wheel off and put it into the tire/wheel tank with an air hose clamped on

Bubbles from the steel rim area about 1/2” below the rim edge.

Not just a pin hole bubble stream, but from a crack about 2 inches wide.

The steel wheels (common and rare to have ‘mags’) and the owner asked who installed that wheel/tire.

Guy said out on the road and had a blowout and a gas station filled it by using a tire/wheel from out back...

It was a “P” class (passenger class) tire on a car wheel

Edit...here is an image of a wheel NOT rated for LT load range E tires. Tires having a rating of 80PSI and this wheel has a 60PSI rating

[time2roll]

jimcatinmi wrote:
good morning, I just switched from a tt to a 5th wheel and I noticed when hooked up my tires look a little low. Should I set the psi to what the tire says or what's on the door?

Truck... I would add up to 10 psi to the rear tires and 5 psi to the front, not to exceed the sidewall max.

Trailer... Run the sidewall max.

I assume you are within the truck specifications. If you might be over the truck payload rating go to the sidewall max on the rears and get to a scale. Post the results and ratings.

[Grit_dog]

Since we’re off topic already....
Yes that’s a lot of trailer for a 1/2 ton but a 2100lb pin weight plus hitch will not tank a HD 1/2 ton. But you’ll be right at or a bit over the 4500lb rating of the 9.75 axle....if that weight is accurate.

[Old-Biscuit]

10,735# GVWR on that trailer
DRY weight is 7855# with a DRY pin percentage of 20%
20% Wet pin......2150# pin weight
31'10" length
12'1" height

Load Assist Shocks do NOT add weight carrying capacity...they just help level out and overloaded suspension

Too much trailer/too little of truck

Hit the SCALES and find out how much you are exceeding trucks ratings.....especially RAWR/Tire MAX Load Ratings

[12th_Man_Fan]

cougar28 wrote:

12th Man Fan wrote:
The sticker on your door reflects the inflation for max. GWR of your truck. That is the info I use to inflate my tires. There is no use going higher unless you are overloading the truck.

But what if the tires is not factory? Did some put lighter on it at some point- maybe heavier ply tires.

If we are not talking factory equipment , all bets are off.

[Grit_dog]

Regarding tires. Air up to max inflation on sidewall if needed. (Sounds like they’re squishy now?). But know you may not need max pressure if they’re 80 psi rated tires.
Approximate your weight on the rear axle. IE 2500lb truck, 500 hitch n gear, 1500 pin.
Look up a load/ pressure chart for your size tire and it will tell you the right pressure. Then maybe fine tune it to preference. You’ll be surprised how low of pressure may be “acceptable” based on the charts and typically I like aired up a bit from the minimum for greater stability
Congrats on the new rig!

Just to dispel a couple rumors that will likely get brought up.
Yes 1/2 ton truck rims will handle up to 80 psi just fine.
No, you won’t break your axle if your at or a bit over the “rating.”
Yes, you can tow a smallish 5ver just fine with a 1/2 ton. Whether it’s the “best” or “ideal” is subjective, but within reason there is no inherent problem with doing it.

Have fun w the new camper!

[dodge_guy]

What is the load rating of the LT tires you put on!

[Lwiddis]

Water alone, JDC1,....

[jdc1]

Before you add propane, water, gear, hitch and PEOPLE......you only have 300 pounds of capacity left.

[Desert_Captain]

Get your rig weighed as it will be used and then check the load inflation chart from the tire manufacturer and inflate accordingly.

:C

[jimcatinmi]

Thanks so much for the info, yes we are at the limit for the truck I did put Monroe load assist shocks on the rear and that did help. the pin weight is 1400lb but that's not loaded. I will look at the tires for the numbers when I get home but I do know its a Michelin LT tire.