Tires on 2020 RAM 2500

[PSFORD99]

Originally Posted by kowbra

While completely correct and I agree with the recommendations, I'll provide alternative data for consideration.

First note that the manufacturers recommended MAX pressure is to support the manufacturers rated MAX load. IOW, you cannot safely achieve rated GVWR with less than the manufacturers recommended tire pressure.

However, heavy duty pickup trucks are also extremely variable in their weights compared to other classes of vehicle on the road. Commercial work trucks run loaded almost all the time, so they run recommended max pressure every day, no question. On the opposite side, cars often have only a few hundred pounds of difference between empty and loaded, so MAX pressure also works good; it supports the weight and conveys a smooth ride whether empty or loaded.

Compare the above to the HD pickup, especially the rear axle. For a 3500 class vehicle, the rear axle weight could vary by as much as 4000lbs or more during typical driving conditions -empty vs loaded. What tire pressure would be adequate for empty weights vs loaded weights? We don't have to guess, those ratings are published.
The OP didn't provide tire size, but PSFORD99 provided his tire size at LT275/70R18.
https://tirepressure.com/lt275-70r18-tire-pressure

Based on the tire pressure chart, and given that PSFORD99s 2014 RAM 3500 has a 6000lb front axle and a 7000lb rear axle, you can see why the manufacturer has recommended 65psi front and 80psi rear.

To determine what might be a safe empty tire pressure, lookup the information for the truck, in this case,
http://www.rambodybuilder.com/2014/d...ammlup3500.pdf

Assuming the most popular RAM, a Laramie cummins crew cab short box 4x4, the empty axle weights are; ~4800lbs front axle and ~3000lbs rear.

Back to the tire charts and you could see that empty the rear axle is so light that even 35psi would technically work; and the front axle, empty, could go as low as 40psi. But at those pressures most LT tires would feel very squirmy and have poor wear.

What's the point of the above? There is a bit of art meets science here. If you are loaded, use the max tire pressure recommended by the manufacturer on the door sticker (not the max on the sidewall).
But, if driving empty, you can easily lower tire pressure by a considerable amount and still safely carry the load. The limiting factors then become how does the tire feel and how does it wear?
Most LT tires will feel ok at 55psi, and some feel ok below that.

Then, if you want to check on wear, air the tires to where it feels good empty, and do a chalk test. Put a thick chalk line across the tire, drive ahead on dry pavement and see where the chalk makes contact. If even across the tire, then the pressure will be fine.

Again, I completely understand that the "correct" answer is to follow the stated manufacturers recommendations. But running tires at 80psi to support a 7000lb axle load then only loading them at 3000lbs, will not provide a smooth ride. So if you want a nicer ride empty, the above provides an example of research to support doing that safely.

Just make sure to air back up when loading up.

hth

Brad

I agree. 80 psi, I know i'm covered for the max load of those rears when towing . As said my fronts stay at 60, thats whats on the door . I don't go to inflation charts ,but by experience air downing , no issues going down to 40-50 on the rears running unloaded . I usually hit somewhere in that range when releasing the air , I shot for around 45, if its 45-50 , then I just match up the other side .

[kowbra]

Originally Posted by PSFORD99

I agree. 80 psi, I know i'm covered for the max load of those rears when towing . As said my fronts stay at 60, thats whats on the door . I don't go to inflation charts ,but by experience air downing , no issues going down to 40-50 on the rears running unloaded . I usually hit somewhere in that range when releasing the air , I shot for around 45, if its 45-50 , then I just match up the other side .

An interesting note on the 2019+ RAM 2500s compared to the prior generation.
For the 2014-2018 RAM 2500s, the door stickers were 65psi front, 80psi rear; which matched the recommendations for the 3500s of the same generation.

However, in the latest generation 2019+ 2500s, the door stickers are 65psi all the way around, while the 3500s have stayed with the 65/80psi split as before. (at least in the Laramie and higher trims).

The reality all along is that 65psi was enough for tires on the rear axle for a 2500 to meet it's GVWR (which has not changed). For some reason, in the prior generation the manufacturer recommended to "overinflate" the rear tires beyond what was needed for the rated load, but has now adjusted down to more accurately match the rated load.

So, for the OP @Chief Brown, with a 2020 RAM 2500, run the recommended 65psi all the way around when loaded. And, if the ride is harsher than you like when empty, consider airing down a bit on the rear when empty, but air back up when loaded.


Brad

[PSFORD99]

Originally Posted by kowbra

An interesting note on the 2019+ RAM 2500s compared to the prior generation.
For the 2014-2018 RAM 2500s, the door stickers were 65psi front, 80psi rear; which matched the recommendations for the 3500s of the same generation.

However, in the latest generation 2019+ 2500s, the door stickers are 65psi all the way around, while the 3500s have stayed with the 65/80psi split as before. (at least in the Laramie and higher trims).

The reality all along is that 65psi was enough for tires on the rear axle for a 2500 to meet it's GVWR (which has not changed). For some reason, in the prior generation the manufacturer recommended to "overinflate" the rear tires beyond what was needed for the rated load, but has now adjusted down to more accurately match the rated load.

So, for the OP @Chief Brown, with a 2020 RAM 2500, run the recommended 65psi all the way around when loaded. And, if the ride is harsher than you like when empty, consider airing down a bit on the rear when empty, but air back up when loaded.


Brad

I keep seeing the 65psi for the front, yet mine is 60psi. Every time I read this I go out ,and look again , thinking its going to change to 65 psi ,so far it hasn't

My truck is a 2014 3500 Laramie Megacab SRW. And its had that 60 psi on the door placard since I bought it new 60 psi is what I have ran them front tires for the past seven years .

[kowbra]

Originally Posted by PSFORD99

I keep seeing the 65psi for the front, yet mine is 60psi. Every time I read this I go out ,and look again , thinking its going to change to 65 psi ,so far it hasn't

My truck is a 2014 3500 Laramie Megacab SRW. And its had that 60 psi on the door placard since I bought it new 60 psi is what I have ran them front tires for the past seven years .

Ah, I think it's because you have the 18" tires. I'm going off the trim levels that come with the 20" tires.
Sorry, I should have thought of that before.

Brad

[PSFORD99]

Originally Posted by kowbra

Ah, I think it's because you have the 18" tires. I'm going off the trim levels that come with the 20" tires.
Sorry, I should have thought of that before.

Brad

I suppose thats the reason ,although the front end of that 3500 is as heavy or heavier then the 2500 . I guess the only to know why is to see a weight chart , obviously 60 psi reaches the weight needed on my 18" tire ,as to where the 20's need 65 to achieve the same weight rating .

[CalandLinda]

Originally Posted by kowbra

An interesting note on the 2019+ RAM 2500s compared to the prior generation.
For the 2014-2018 RAM 2500s, the door stickers were 65psi front, 80psi rear; which matched the recommendations for the 3500s of the same generation.

However, in the latest generation 2019+ 2500s, the door stickers are 65psi all the way around, while the 3500s have stayed with the 65/80psi split as before. (at least in the Laramie and higher trims).

The reality all along is that 65psi was enough for tires on the rear axle for a 2500 to meet it's GVWR (which has not changed). For some reason, in the prior generation the manufacturer recommended to "overinflate" the rear tires beyond what was needed for the rated load, but has now adjusted down to more accurately match the rated load.

So, for the OP @Chief Brown, with a 2020 RAM 2500, run the recommended 65psi all the way around when loaded. And, if the ride is harsher than you like when empty, consider airing down a bit on the rear when empty, but air back up when loaded.


Brad

The vehicle manufacturer installs OE ties to support the GAWR loads. In doing so they are providing load capacity reserves.

NOTE: Let the USTMA be your guide, not so and so at such and such a place.

https://www.ustires.org/sites/defaul...TruckTires.pdf

[kowbra]

Originally Posted by CalandLinda

The vehicle manufacturer installs OE ties to support the GAWR loads. In doing so they are providing load capacity reserves.

NOTE: Let the USTMA be your guide, not so and so at such and such a place.

https://www.ustires.org/sites/defaul...TruckTires.pdf

Understood, and RAM changed for their reasons that are not stated. I was noting that the new rear tire pressure recommendations for the 2500s more accurately match the actual rated GAWR of the truck. The GAWR has not changed between generations, yet now with the identical tires on the same rims, RAM has lowered the recommended rear pressure from 80psi to 65psi (on the 20" tires).

With respect, the USTMA is not relevant to the changes that RAM made. USTMA describes the tires and the tire manufacturer recommendations, not the vehicle manufacturer recommendation changes I referenced.

Brad

[CalandLinda]

Originally Posted by kowbra

Understood, and RAM changed for their reasons that are not stated. I was noting that the new rear tire pressure recommendations for the 2500s more accurately match the actual rated GAWR of the truck. The GAWR has not changed between generations, yet now with the identical tires on the same rims, RAM has lowered the recommended rear pressure from 80psi to 65psi (on the 20" tires).

With respect, the USTMA is not relevant to the changes that RAM made. USTMA describes the tires and the tire manufacturer recommendations, not the vehicle manufacturer recommendation changes I referenced.

Brad

Different designated tire sizes use different load inflation charts. The correct information for the installed OE tires is on the vehicle certification label.

[kowbra]

Originally Posted by CalandLinda

Different designated tire sizes use different load inflation charts. The correct information for the installed OE tires is on the vehicle certification label.

Agree, but that's not the point under discussion here.

In this case, for 20" tires, the 2014-2018 RAM 2500 had a door label with 65f/80r and 1 year later the 2019 RAM 2500 changed to 65/65.
Yet GAWR, GVWR, tire size, even tire brand - all identical between the 2 years. (in the case of my example, Firestone Transforce AT LT285/60R20).
Obviously nothing changed about the tire load chart, but the vehicle manufacturer made the change to the label.
I merely noted it.


Brad

[CalandLinda]

Originally Posted by kowbra

Agree, but that's not the point under discussion here.

In this case, for 20" tires, the 2014-2018 RAM 2500 had a door label with 65f/80r and 1 year later the 2019 RAM 2500 changed to 65/65.
Yet GAWR, GVWR, tire size, even tire brand - all identical between the 2 years. (in the case of my example, Firestone Transforce AT LT285/60R20).
Obviously nothing changed about the tire load chart, but the vehicle manufacturer made the change to the label.
I merely noted it.


Brad

The FMVSS standards says the vehicle manufacturer must provide tires that are appropriate for the vehicle they are fitted to. Appropriate meaning the tires must have a load capacity that supports the load of the axle they are fitted to via recommended cold inflation pressures. Does 3085# of load capacity for each tire (6170# total) support your vehicle certified rear axle? Are they LRD or LRE? 3085# is the maximum load capacity the LRD can provide at 65 PSI.

[kowbra]

Originally Posted by CalandLinda

The FMVSS standards says the vehicle manufacturer must provide tires that are appropriate for the vehicle they are fitted to. Appropriate meaning the tires must have a load capacity that supports the load of the axle they are fitted to via recommended cold inflation pressures. Does 3085# of load capacity for each tire (6170# total) support your vehicle certified rear axle? Are they LRD or LRE? 3085# is the maximum load capacity the LRD can provide at 65 PSI.

LRE 3640lbs rating each, same between all models discussed.
But again, totally unrelated to the point.

Brad

[CalandLinda]

Originally Posted by kowbra

LRE 3640lbs rating each, same between all models discussed.
But again, totally unrelated to the point.

Brad

At 65 PSI those LRE tires provide 3085# of load capacity.

[kowbra]

Originally Posted by CalandLinda

At 65 PSI those LRE tires provide 3085# of load capacity.

Yes, I know that.
And in 2019 RAM made the decision that 65psi was all that was needed to support the rear GAWR of 6000lbs of the 2500 models, whereas the year before they recommended the max pressure of 80psi or 3640lbs load capacity of each tire -- on the same truck model, with the same specs and using the same tires. The 80psi never was needed for those tires with the 6000lbs rear GAWR of the 2500 but that's what RAM put on the placard for years.

Which is kind of the point I've been trying to make all along...

That is also why I shared tire pressure rating charts in an earlier post, so those asking about airing down their tires when empty could do so in an informed and safe way. Despite you seeming to dismiss the source, what I linked to is a tool that gathers information from the recommendations of USTMA and presents it in a way that someone can easily find the load chart information for their tire size.

But I think you know this Cal. And I think you know why pickup truck manufacturers used to put a tire load pressure chart in their manuals, and why that changed in ~2007. And why even though vehicle manufacturers don't provide those tire pressure load charts, they are still relevant (as you've cited them).

I think you speak as a tire expert, and I speak as a former commercial tractor/trailer operator with over a million miles under my butt. So I think in the end our differing background means we are writing about different sides of the same issue, and perhaps agreeing and disagreeing at the same time.

So I'm going to stop writing about this now.
Hopefully what I've shared is of practical value to the OP and to the intent of the thread.

All the best!
Brad

[CalandLinda]

Originally Posted by kowbra

Yes, I know that.
And in 2019 RAM made the decision that 65psi was all that was needed to support the rear GAWR of 6000lbs of the 2500 models, whereas the year before they recommended the max pressure of 80psi or 3640lbs load capacity of each tire -- on the same truck model, with the same specs and using the same tires. The 80psi never was needed for those tires with the 6000lbs rear GAWR of the 2500 but that's what RAM put on the placard for years.

Which is kind of the point I've been trying to make all along...

That is also why I shared tire pressure rating charts in an earlier post, so those asking about airing down their tires when empty could do so in an informed and safe way. Despite you seeming to dismiss the source, what I linked to is a tool that gathers information from the recommendations of USTMA and presents it in a way that someone can easily find the load chart information for their tire size.

But I think you know this Cal. And I think you know why pickup truck manufacturers used to put a tire load pressure chart in their manuals, and why that changed in ~2007. And why even though vehicle manufacturers don't provide those tire pressure load charts, they are still relevant (as you've cited them).

I think you speak as a tire expert, and I speak as a former commercial tractor/trailer operator with over a million miles under my butt. So I think in the end our differing background means we are writing about different sides of the same issue, and perhaps agreeing and disagreeing at the same time.

So I'm going to stop writing about this now.
Hopefully what I've shared is of practical value to the OP and to the intent of the thread.

All the best!
Brad

Just a few notes: There was a major NHTSA tire rules committee meeting in 2007 and many were changed. It was reconfirmed that the Tire and Rim Association (TRA) would oversee and standardize all tire load inflation charts.

With all of your experience in the trucking industry you're probably quit efficient in quoting their rules and regulations as presented in FMCSA documents. Rules and procedures in the FMCSA are not applicable to vehicles built under the guidance of FMVSS.

Under FMVSS standards it's always the responsibility of the vehicle manufacturer to set recommended cold inflation pressures for OE tires.

You can't argue with them and win if the tires meet the minimum standard for the vehicle they are fitted to. (So says NHTSA)

[sourdough]

Most folks on the forum have towed for a while; know their tire specs and limitations and have learned what it takes to "fit" their situation and keep safe. Repeated references to "one size fits all" government regulations that in reality have no idea of what we encounter every day gets old. Are they useful if you don't know them? Probably. Do they apply "literally" to every comment made in this discussion - not at all IMO. YMMV.

[kowbra]

Originally Posted by sourdough

Most folks on the forum have towed for a while; know their tire specs and limitations and have learned what it takes to "fit" their situation and keep safe. Repeated references to "one size fits all" government regulations that in reality have no idea of what we encounter every day gets old. Are they useful if you don't know them? Probably. Do they apply "literally" to every comment made in this discussion - not at all IMO. YMMV.

Thanks @sourdough and well said!

I agree that this forum seems to have many very experienced members. For those less experienced, hopefully I've shared information to help them do their own research and understand their own tire specs and load ratings.

Brad

[Camp CA]

Originally Posted by Chief Brown

............The door placard says run 60# air in tires. The cold tire pressure is 80# on side of tire. My fiver is 10,200 dry weight. So trying to determine where should I set the tire pressures?.............

My 2016 Ford F350 door placard specifies 65 psig for front and rear tires and cold tire pressure is 80 psig. When my 15,000-16,000 lb trailer is loaded I will incease the 4 rear tires to 80 psig with my Viair 40047 400P-RV Automatic Portable Compressor Kit, which provides a very comfortabe tow. When not towing I will deflate the rear tires to 65 psig. You might find the etrailer thread on this qustion helpful.

https://www.etrailer.com/question-239814.html

[laverdur]

One way is to weigh your rig when packed for a trip and then use the tire manufacturer's load/inflation table to determine the lowest tire pressure that will do the job. My TV door sticker calls for 65 psi in front and 80 psi in the rear. With 80,000 miles of towing and checking tire wear with a tread depth gauge, I run 71 psi in front ans 82 psi in the rear. This gives perfect tire wear. One might challenge the 82 psi in the rear on load range E tire but that 2 psi is well within the range of error for most tire gauges and well below the pressure that the tire reaches at highway speeds on a warm sunny day even when inflated to 80 psi.

[azwiz]

look on the tires for best pressure loaded

[kowbra]

Originally Posted by azwiz

look on the tires for best pressure loaded

Before you beat that horse, you may want to make sure to share accurate information. What you've shared is incorrect.

The pressure on the tire sidewall is the max that it can hold. But since the tire could be installed on many different vehicles, the proper pressure for a tire installed on your vehicle - is on your vehicle.
Specifically, for your truck it's on a placard on the drivers door jam. For your 5th wheel, on a placard on the front drivers side corner of the rig.

Brad