Tire pressure confusion

[Art in Phoenix]

I’ve done a search and can’t seem to find the answers to these questions. I apologize in advance if this has been discussed many times.

2021 3500 limited longhorn High output diesel, 8 foot bed, automatic air leveling, 4 x 4, dual rear wheels, 5,000 lbs payload capacity
Tires: Nexen Roadian HTX RH5 LT235/80R17 load range E, Maximum tire pressure 80 psi at 2,835 lbs in dual rear wheel application

I purchased this truck several months ago with these tires installed and the dealer had the right side tire pressures higher than the left side by 5 to 7 pounds. The B pillar states rear tires should be 65 psi. The rear tires were originally inflated at 87 psi - I did not change it. I put 9,400 miles on with very little load in the bed. It has been a very rough ride.

I took the truck in for a warranty repair as the fuel pump in the 50 gallon tank had failed (fuel gauge on the dash was stuck at full). Dealer told me the sending unit on the pump was damaged. I had them change the oil and rotate the tires while it was there. The service advisor suggested adjusting the tire pressures to the B pillar tag. It appears the higher pressure tires are now on the opposite side and they were not adjusted (I monitored and checked after a 40 mile drive).

We will be going full-time RVing with a fifth wheel hitch weight around 4000 pounds. I will probably end up close to the maximum payload after fuel, passengers, and incidentals.

Should the rear tires all be set to 65 psi cold regardless of payload conditions? Has there been any damage introduced with the high pressure on the rear tires that I should be looking for? Are these tires correctly matched to the truck (the tire sizes do match the tag recommendations) and why is there such a discrepancy between Ram’s tire pressure recommendation and the actual recommendation on the tire?

 

[Randy Grant]

I’ve done a search and can’t seem to find the answers to these questions. I apologize in advance if this has been discussed many times.

2021 3500 limited longhorn High output diesel, 8 foot bed, automatic air leveling, 4 x 4, dual rear wheels, 5,000 lbs payload capacity
Tires: Nexen Roadian HTX RH5 LT235/80R17 load range E, Maximum tire pressure 80 psi at 2,835 lbs in dual rear wheel application

I purchased this truck several months ago with these tires installed and the dealer had the right side tire pressures higher than the left side by 5 to 7 pounds. The B pillar states rear tires should be 65 psi. The rear tires were originally inflated at 87 psi - I did not change it. I put 9,400 miles on with very little load in the bed. It has been a very rough ride.

I took the truck in for a warranty repair as the fuel pump in the 50 gallon tank had failed (fuel gauge on the dash was stuck at full). Dealer told me the sending unit on the pump was damaged. I had them change the oil and rotate the tires while it was there. The service advisor suggested adjusting the tire pressures to the B pillar tag. It appears the higher pressure tires are now on the opposite side and they were not adjusted (I monitored and checked after a 40 mile drive).

We will be going full-time RVing with a fifth wheel hitch weight around 4000 pounds. I will probably end up close to the maximum payload after fuel, passengers, and incidentals.

Should the rear tires all be set to 65 psi cold regardless of payload conditions? Has there been any damage introduced with the high pressure on the rear tires that I should be looking for? Are these tires correctly matched to the truck (the tire sizes do match the tag recommendations) and why is there such a discrepancy between Ram’s tire pressure recommendation and the actual recommendation on the tire?

When I tow I run the tires at max rating. BTW, don't rely on the dash tpme totally. Check the tires with a good tire gauge. When empty I run at a lower psi for a softer ride.

 

[LouM]

The tire pressure on your trucks placard is the correct pressure for the tire size and rating on the placard for the max weight the truck is rated for.
The max pressure listed on the tire is strictly for the tire, that is the maximum pressure that tire should be cold inflated to,
regardless of the vehicle it may be installed on it doesn't matter if it's a half ton or a 2 ton truck.

Running a tire a max pressure will usually result in less tire tire with the centers getting worn out before the edges,
as well as getting less traction.

 

[GTyankee]

OK, tire pressures can be confusing

The Ram Engineers made the truck, they weighed the truck & they know as much as anyone about the truck.
Those same Engineers spec'd out YOUR Ram & had the Door Sticker made specifically for your Ram.
You should keep in mind that you need a bit more air when you are carrying or hauling something, than when you are are running empty.

.....................................................................

Tire Manufacturers make tires for many sizes & brands of vehicles
Say that they make a tire, it may fit on anything from a Farm Vehicle, a Landscaper trailer, a Dually, someones Hot Road.
So they just have to decide on a tread, off road or highway, how tall & or wide, how fast it may need to go.
With all of that in mind, they don't have to consider whether it will go on a Ram, Ford, Toyota or a Rolls Royce.
They just make a tire & the different companies engineers go through a catalog & decide which will or won't work.

So what is imprinted on the Tires sidewall, just lets everyone know what stresses a particular tire will with stand.

So just go by your door stickers & whether you are running heavy or light, Then air up for the heavy load & let the air down when running normally

 

[OC455]

I run 65psi on the rears and 78psi on the fronts.

 

[crash68]

^^^^ what @LouM stated

Should the rear tires all be set to 65 psi cold regardless of payload conditions?

If running empty, lots of people lower the air pressure in the rears for a better ride.

 

[OC455]

I purchased this truck several months ago with these tires installed and the dealer had the right side tire pressures higher than the left side by 5 to 7 pounds. The B pillar states rear tires should be 65 psi. The rear tires were originally inflated at 87 psi - I did not change it. I put 9,400 miles on with very little load in the bed. It has been a very rough ride.

My tire pressures were all over the place too when I got my truck from the dealer...first thing I did was set the four rear tires to 65psi. & then the fronts I set to lower than 80psi. I've noticed when the outside temps get higher than normal, and I start going places the tire pressures increase. I keep the fronts tires below max and it seems to help more. Before I head out with the travel trailer tomorrow, going to drop the front tires to 75psi.

 

[runamuck]

the numbers can be confusing. one of the major causes of tire failure is under inflation so the tires on my laramie have 51 psi max inflation but the door pilar says to fill to 34 psi..seems to me like if i do that i am taking a chance on tire failure but posters on the rv and truck sites say go by the door pilar numbers. seems to me that like any other part on the truck..the tires should be operated at the mfr's suggested settings. there is a lot of difference between 34 and 51. IMHO

 

[tjfdesmo]

I weighed my '19 dually the other day, I have a 55 gal Titan fuel tank in place of the OEM tank, and it was nearly full, the DEF tank was at about 1/4. With just me in the truck it scaled at 9,360, and 5,400 was on the steer axle. Based on a Load/Inflation table, available on tire mfr site, the fronts should be kept close to the door tag 80 lbs. I adjust the rears to suit what I am doing. Empty, with less than 4,000 lbs across four tires, 40 psi is plenty. When pulling my prior toy hauler that put almost 4,800 lbs on the hitch, I ran with 65 psi, per the door tag.

TBH, and you have probably read this already, I would ditch the Nexens ASAP.

 

[pictureofuu]

I never pay attention to the sticker. Those psi numbers are for the stock tire rating that came on the truck. Always pay attention to the sidewall. Even at the dealership I argue with them. I dont have stock tires and mine max inflation is 70 psi. But they go by the sticker and inflate to 80 psi. That is actually a safety issue. But they keep saying that is what the sticker says. Yes for stock original factory tires. I asked the dealer, is that factory stock original tires. They could not answer my question. WOW!

So now when I go in for any maintenance (which I only do cause still under warranty) I tell them to leave tire pressure alone.

I did have one time out of state on a vacation and did an oil change. They called me a half hour later and said we need you to bring the truck back ASAP. We did the wrong air pressure in your tires and its a safety issue. They acutally admitted it, good for them. I am waiting for the day that something like this happens and there is a lawsuit somewhere.

 

[LouM]

Well as they say different strokes for different folks;
you appearently have a lighter duty tire on your truck then it originally had,
so I would assume that you are not using the full capabilities of your truck.
But are instead inflating your tires to the maximum for there capabilities.

 

[Irishthreeper]

I’ve done a search and can’t seem to find the answers to these questions. I apologize in advance if this has been discussed many times.

2021 3500 limited longhorn High output diesel, 8 foot bed, automatic air leveling, 4 x 4, dual rear wheels, 5,000 lbs payload capacity
Tires: Nexen Roadian HTX RH5 LT235/80R17 load range E, Maximum tire pressure 80 psi at 2,835 lbs in dual rear wheel application

I purchased this truck several months ago with these tires installed and the dealer had the right side tire pressures higher than the left side by 5 to 7 pounds. The B pillar states rear tires should be 65 psi. The rear tires were originally inflated at 87 psi - I did not change it. I put 9,400 miles on with very little load in the bed. It has been a very rough ride.

I took the truck in for a warranty repair as the fuel pump in the 50 gallon tank had failed (fuel gauge on the dash was stuck at full). Dealer told me the sending unit on the pump was damaged. I had them change the oil and rotate the tires while it was there. The service advisor suggested adjusting the tire pressures to the B pillar tag. It appears the higher pressure tires are now on the opposite side and they were not adjusted (I monitored and checked after a 40 mile drive).

We will be going full-time RVing with a fifth wheel hitch weight around 4000 pounds. I will probably end up close to the maximum payload after fuel, passengers, and incidentals.

Should the rear tires all be set to 65 psi cold regardless of payload conditions? Has there been any damage introduced with the high pressure on the rear tires that I should be looking for? Are these tires correctly matched to the truck (the tire sizes do match the tag recommendations) and why is there such a discrepancy between Ram’s tire pressure recommendation and the actual recommendation on the tire?

I might be mixing apples and oranges but my ‘21 2500/6.4 calls for 60 front, 65 rear. I’ve pulled a 5th wheel most of the 12k miles I have on it with 70 in the rear and have rotated twice. The Firestones still look almost brand new. Good luck with the full timing, we’ve been at it almost a year and love it.

 

[Doug Ram]

OP:

You should have tires that are higher rated both for psi and weight than your truck's sticker. However, if your tires require 80 PSI to carry the same load as what the truck is stamped to carry at 65 PSI, you have an issue: You have to up the tire pressure to that 80 psi to carry what the truck is designed to do with tires at 65 psi. The truck will ride rough and tire grip will not be as good.

Whatever the truck tag maximum numbers are for load and tire pressure, you cannot go over the maximum load or pressure numbers stamped on the tires.

Examples:
1. If the truck tag says 80 max PSI / 10,000 lbs max weight (including cargo), and the tires are stamped 70 psi / 3,000 lbs each (for 12,000 total) max, then you are OK to carry the truck's capacity up to 10,000 at only 70 PSI. In this case the tires can clearly carry more than what the truck is designed for.

2. If the truck tag says 65 psi / 10,000 maximum, and the tires are stamped 70 psi/ 2500 lbs each (for a total of load of 10,000 max), you will need to pump the tires to 70 psi if you want to carry 10,000 lbs. Putting only 65 psi in the tires reduces what they can carry to less than what the truck can carry. The truck will ride harder at 70 psi and tire grip will be reduced.

My rule of thumb is that when I buy tires, it's best if the tires maximum pressure and load capacity are about 25% higher than the truck's. That way there is some margin for safety, in that you know the tires can carry a bit more than what the truck is designed for.

 

[AZtorque]

I run 78PSI front and 38PSI empty, which is still more than I need. Lower rear pressure helped my ride tremendously. When I tow my 40' toy hauler, I inflate to 80 front and 65 rear. If you can find it online, your tires have a PSI load chart that can guide you. Below is from a chart for my BFG KO2's

 

[JRS950]

I run 78PSI front and 38PSI empty, which is still more than I need. Lower rear pressure helped my ride tremendously. When I tow my 40' toy hauler, I inflate to 80 front and 65 rear. If you can find it online, your tires have a PSI load chart that can guide you. Below is from a chart for my BFG KO2's

I do the same on my 18 dually. Other than the hassle of airing up before I tow, it works great.

View attachment 475245

Not sure on brand but we did a billet convertor, line pressure booster, upgraded a bunch of stuff I dont know what it is honestly. Pistons, accumulators? He did some modifications to the valve body. He told me step by step everything he did and honestly I don't know a lot about transmissions so I just told him to go with and and paid him. I think he mentioned using sonnax parts.

The insurance company is footing the bill for the replacement trailer including the add ons that we installed ourselves that the dealer will now install (Slide topper, vent covers, rear camera).
They negotiated the price with Lazy Days corporate. Basically they are paying the 2021 pricing not the inflated 2022 pricing (Up about 15%). It also includes registration fees and tax.
It is only costing us our $500 deductible (that we should eventually get back).

But we did lose some items, probably about $600 worth that were too minor or that we were not able to include such as new Good Year tires that were balanced and had metal valve stems, a bumper cargo hitch mount, etc.

 

[Lordac]

My tire pressures were all over the place too when I got my truck from the dealer...first thing I did was set the four rear tires to 65psi. & then the fronts I set to lower than 80psi. I've noticed when the outside temps get higher than normal, and I start going places the tire pressures increase. I keep the fronts tires below max and it seems to help more. Before I head out with the travel trailer tomorrow, going to drop the front tires to 75psi.

Your door pillar has the "recommended" pressures listed. With a large more commercial truck that is an arbitrary thing. I am currently running a 2014 1500, (But I have a 3500 Diesel SRW on order) and I tow an 8000 pound trailer. The original tires on the truck were great if you didn't tow, however the sidewalls were too soft and squishy so I went went with a more stiff sidewall and higher capacity tire. Now the door pillar is basically incorrect because it was for a lesser capacity tire. My Original tires were supposed to run at 35PSI with a max of 40. My new tires run at 38 with a max of 51. Weight rating is up as well. Originals were 2610 new tires are 2998. Big difference in towing. Because your tires have a max pressure does not mean that you should run them unloaded at that pressure. I only put my tires to 51psi when towing, otherwise I run right around 41psi. My wear has been fine. That's a cold tire pressure. When cold and set at 50psi and running at 78 degrees outside they run up to about 55psi, Also, know that "look" is not a great indicator. I work with 2500 SRW and 3500 DRW transit vans They have 80psi in the rear tires and 65 in the front. Because the sidewalls of these tires are so firm you could run a tire 35psi under inflated and not notice that it's at the wrong pressure. That's a possible danger especially if the van is loaded with passengers.

My final take. Tries are in my opinion, are the most important item to keep a close eye on. So much depends on them. If you want a softer ride, look at the tire, set just above minimum pressure. If you're loading up then set at max. So I guess pressure is really dependent on the situation.

 

[Lordac]

I run 78PSI front and 38PSI empty, which is still more than I need. Lower rear pressure helped my ride tremendously. When I tow my 40' toy hauler, I inflate to 80 front and 65 rear. If you can find it online, your tires have a PSI load chart that can guide you. Below is from a chart for my BFG KO2's
View attachment 475245

Love the chart.

 

[Elvira]

Tire pressures have so many variables to contend with. The door sticker is usually the way to go and stay within those limits. Certain circumstances can change with the vehicle, ply rating, loads etc. If the ply rating is close to oem, then use the door sticker as reference. If you have installed much tougher tires for heavier loads or what ever reason, the tire manufacture ratings will fall into place, but tire manufacturers can only approximate what you are going to use their tire for, heavy loads, off-road etc. They don't actually know the weight of your vehicle or your usage for their tires. It is best to keep tires close to factory recommendations, ply rating, load rating and air pressures. You can use the chalk test to regulate the perfect pressures by visual tread pattern on a tire not oem suited for the vehicle. The tps system is close, but not really accurate...observe as a reference, but always check with an accurate gauge on occasion.

 

[OC455]

Your door pillar has the "recommended" pressures listed. With a large more commercial truck that is an arbitrary thing. I am currently running a 2014 1500, (But I have a 3500 Diesel SRW on order) and I tow an 8000 pound trailer. The original tires on the truck were great if you didn't tow, however the sidewalls were too soft and squishy so I went went with a more stiff sidewall and higher capacity tire. Now the door pillar is basically incorrect because it was for a lesser capacity tire. My Original tires were supposed to run at 35PSI with a max of 40. My new tires run at 38 with a max of 51. Weight rating is up as well. Originals were 2610 new tires are 2998. Big difference in towing. Because your tires have a max pressure does not mean that you should run them unloaded at that pressure. I only put my tires to 51psi when towing, otherwise I run right around 41psi. My wear has been fine. That's a cold tire pressure. When cold and set at 50psi and running at 78 degrees outside they run up to about 55psi, Also, know that "look" is not a great indicator. I work with 2500 SRW and 3500 DRW transit vans They have 80psi in the rear tires and 65 in the front. Because the sidewalls of these tires are so firm you could run a tire 35psi under inflated and not notice that it's at the wrong pressure. That's a possible danger especially if the van is loaded with passengers.

My final take. Tries are in my opinion, are the most important item to keep a close eye on. So much depends on them. If you want a softer ride, look at the tire, set just above minimum pressure. If you're loading up then set at max. So I guess pressure is really dependent on the situation.

Yeeeaahhh.....all I was saying was my tire pressures were all over the place when I picked it up from the dealer and I set the psi to where they rode & handled better. 80-90psi is where some of the readings were...

 

[Jcooper427]

I never pay attention to the sticker. Those psi numbers are for the stock tire rating that came on the truck. Always pay attention to the sidewall. Even at the dealership I argue with them. I dont have stock tires and mine max inflation is 70 psi. But they go by the sticker and inflate to 80 psi. That is actually a safety issue. But they keep saying that is what the sticker says. Yes for stock original factory tires. I asked the dealer, is that factory stock original tires. They could not answer my question. WOW!

So now when I go in for any maintenance (which I only do cause still under warranty) I tell them to leave tire pressure alone.

I did have one time out of state on a vacation and did an oil change. They called me a half hour later and said we need you to bring the truck back ASAP. We did the wrong air pressure in your tires and its a safety issue. They acutally admitted it, good for them. I am waiting for the day that something like this happens and there is a lawsuit somewhere.

You go by the sticker not the sidewall. The rating on the sidewall is only the max pressure the tire is designed to hold NOT the pressure you want to set them to. If the sidewall rating is lower then the sticker then you bought the wrong tires that are not rated for your truck. HTH