Tires on 2020 RAM 2500

[azwiz]

Actually, that's wrong also. Tire company's publish charts for tire pressures corresponding to loads! Placards have long been proven wrong on vehicle door jams.

[kowbra]

Originally Posted by azwiz

Actually, that's wrong also. Tire company's publish charts for tire pressures corresponding to loads! Placards have long been proven wrong on vehicle door jams.

I understand about tire pressure charts. If you were less busy beating horses you might have noticed that was discussed at length earlier in this thread

Can you provide a reference for your claims that placards are incorrect?

Brad

[PSFORD99]

Originally Posted by kowbra

I understand about tire pressure charts. If you were less busy beating horses you might have noticed that was discussed at length earlier in this thread

Can you provide a reference for your claims that placards are incorrect?

Brad

That is interesting , my OEM tires were E rated on my 2014 Ram 3500 rated for 3640 @80 psi. The placard reads 60 psi front 80 psi back. I have to assume weight of the front end requires 60psi to cover the weight ,so I have to assume the front end of that Ram weights less then 3640 ? . So I also have to assume, I will not be able to overload the front end beyond whatever 60 psi gives me . The 80 psi is telling me that its the max weight rating I can apply to those tires 3640, because I have the potential to reach that weight. Does that make sense, and thats the reasoning on the placard ???

[Carl n Susan]

My Ford SRW is also 60/80. I assume they are recommended PSIs. But the rear axle unloaded weighs less than the front axle. Why then the 80 PSI? Is that max? Or the absolutely must run at PSI regardless of load? Then explain why the front is only 60 PSI?

[kowbra]

Originally Posted by azwiz

Actually, that's wrong also. Tire company's publish charts for tire pressures corresponding to loads! Placards have long been proven wrong on vehicle door jams.

Just in case you are still looking, here is a reference for you from NHTSA,
https://www.nhtsa.gov/equipment/tires

The relevant section is part way down, under Tire Pressure. Quote:
"Your tires' proper tire inflation pressure—measured in both kilopascals (kPA) and pounds per square inch (PSI or psi)—can be found on the Tire and Loading Information Label on the driver's side door edge or in your owner's manual."

Once again you've posted incorrect information. I have no interest in arguing here; but it is amazing how much confusion there seems to be about a question as basic as "should I use the sidewalls or the tire placard when setting my tire pressure?"

The answer is simple - use the placard when loading to your maximum weights on your truck, and always on your trailer.
If you are driving your truck empty you MAY wish to air down for better ride quality -but IF and only IF- you have taken the time to educate yourself on load charts for your tires and vehicle so that you maintain safe pressures.

Obviously the horse still needs more beating, as there are some who still don't have the correct, and safe, answer.

Brad

[kowbra]

Originally Posted by PSFORD99

That is interesting , my OEM tires were E rated on my 2014 Ram 3500 rated for 3640 @80 psi. The placard reads 60 psi front 80 psi back. I have to assume weight of the front end requires 60psi to cover the weight ,so I have to assume the front end of that Ram weights less then 3640 ? . So I also have to assume, I will not be able to overload the front end beyond whatever 60 psi gives me . The 80 psi is telling me that its the max weight rating I can apply to those tires 3640, because I have the potential to reach that weight. Does that make sense, and thats the reasoning on the placard ???

Keep in mind, you are referencing the tire capacity for each tire, and you have 2 of them per axle

So, at 80 psi, your tires will provide a bit over 7000lbs of capacity, which matches the rear axle rating. Your front axle is likely 6000lbs, which is why the placard allows for reduced pressure.

hth
Brad

[kowbra]

Originally Posted by Carl n Susan

My Ford SRW is also 60/80. I assume they are recommended PSIs. But the rear axle unloaded weighs less than the front axle. Why then the 80 PSI? Is that max? Or the absolutely must run at PSI regardless of load? Then explain why the front is only 60 PSI?

Yes, you are correct that they state 80psi in order to support the max load on that rear axle.

As to why pickups often rate front tires at lower pressure? The front carries less weight when loaded. And the axle ratings reflect that; a 3500 class SRW pickup commonly has 6000lb rated axles front, 7000lb rear. So, in that example, the placard will be stating the pressures to support min 3000lbs for each front tire, but min 3500lbs for each rear tire. (your tires are likely a typical 3640lbs at 80psi)

Which, again, is why your placard specifies 80psi for those rear tires to support the weight when loaded up. Whereas, for the front axle on my RAM 3500 with the heavy cummins, I weigh about 5000lbs empty and 6000lbs loaded up. So, that's the reason that the recommended 60-65psi (depending on tire) makes sense for the front tires.

But the rear axle tire pressures is where some earlier debate arose - is it ok to air down the tires on my truck when I'm not loaded?

Some would say that the current regulations do not allow for airing down any of the tires below the vehicle placard. And, technically that is correct, ever since 2007. Before that, pickup manufacturers provided tire pressure load charts in the manual to help people decide what was the best tire pressures for loaded vs empty. But, then due to safety issues (think the Firestone blowups) and the EPA, we got both TPMS and the removal of charts to run tires at less than fully loaded pressures.

To use my 2020 RAM 3500 as an example, my empty rear axle weight is only about 3200lbs. So, technically I only need to have 1600lbs of support for each rear tire when empty, but 3500lbs each rear tire when loaded. Obviously no need for the 80psi when empty, and even the 60psi of the front is more than sufficient. (but it would also be silly to air down to something like 15psi just because of a load chart; some common sense needed).

I will quote what I said earlier...
The answer is simple - use the placard when loading to your maximum weights on your truck, and always on your trailer.
If you are driving your truck empty you MAY wish to air down for better ride quality -but IF and only IF- you have taken the time to educate yourself on load charts for your tires and vehicle so that you maintain safe pressures.

hth!
Brad

[PSFORD99]

Originally Posted by Carl n Susan

My Ford SRW is also 60/80. I assume they are recommended PSIs. But the rear axle unloaded weighs less than the front axle. Why then the 80 PSI? Is that max? Or the absolutely must run at PSI regardless of load? Then explain why the front is only 60 PSI?

I am just guessing ,no real idea . But yes I am assuming max weight. To me 60 psi front covers whatever the max weight is , There can't be much weight transfer to the front with a fifth wheel being over the back axle, I would also guess they are figuring when you reach your max weight rating on the rear axle , whatever weight transfer to the front is covered by 60 psi. Again just guessing .

I run 60 psi on my front I never change it, the back unloaded I run about 45 psi .

[kowbra]

Originally Posted by PSFORD99

I am just guessing ,no real idea . But yes I am assuming max weight. To me 60 psi front covers whatever the max weight is , There can't be much weight transfer to the front with a fifth wheel being over the back axle, I would also guess they are figuring when you reach your max weight rating on the rear axle , whatever weight transfer to the front is covered by 60 psi. Again just guessing .

I run 60 psi on my front I never change it, the back unloaded I run about 45 psi .

I agree that is what manufacturers are assuming.

Of course, you could argue that in the real world with all the different combinations of hitches for 5th wheels and goosenecks that the actual load distribution could be different. Which is why it's a good idea to use a CAT scale once in awhile to check your actual loaded weights.
(on class 8+ trucks where weights can vary by thousands of pounds, they have a sliding 5th wheel that can be moved back and forth to get the distribution correct; they have the opposite problem where front axles are often overweight. Usually pickups it's the rear axle that gets overloaded)

I recall looking up your tire information earlier and that 45psi will be able to support ~2400lbs each. So, that will have more than the required capacity for when you're empty.

I do about 55psi all around when empty. I probably could go lower on the rear, but to me it starts to feel a bit mushy (with the tires I'm running). I just have to remember to fire up the Viair before hooking up!

Brad

[azwiz]

LOL got more important fish to fry

[Carl n Susan]

The issue with dropping the rear air pressure when running empty is the builtin Ford TPMS. It dislikes the rear PSi being less than 60.

[CalandLinda]

There is no provision in the FMVSS that allows lowering the vehicle's tire inflation pressures below what has been recommended by the vehicle manufacturer. Unless the vehicle manufacturer has provided a special provisional tire and load placard; or information in the vehicle owner’s manual. Remember; vehicle manufacturers rule tire inflation pressures, OE and replacements.

Inflation pressures from what is recommended to sidewall max are always optional.

[kowbra]

Originally Posted by Carl n Susan

The issue with dropping the rear air pressure when running empty is the builtin Ford TPMS. It dislikes the rear PSi being less than 60.

That's interesting. For 3/4 ton (class 2b), they are required to have a full TPMS which warns if tire pressures are low. For 1 ton (class 3, 10k+) they don't require a full TPMS, more like a TPIS (tire pressure "information" system; still not technically correct, but no consistent definition).
Point is, for your F350, I would have expected similar to my RAM 3500 - it has the sensors, and an area in the display to check the tires, but it will not trigger any warnings.

Likely 60psi instead of 80psi in the rear tires will make for a much softer ride when empty, and could be the happy medium for you.

Brad

[kowbra]

Originally Posted by CalandLinda

There is no provision in the FMVSS that allows lowering the vehicle's tire inflation pressures below what has been recommended by the vehicle manufacturer. Unless the vehicle manufacturer has provided a special provisional tire and load placard; or information in the vehicle owner’s manual. Remember; vehicle manufacturers rule tire inflation pressures, OE and replacements.

Inflation pressures from what is recommended to sidewall max are always optional.

With respect, we know, and I've explained the regulations, why they exist, when they changed and why someone may want to make a different, informed, choice.

Each one is free to make their own choice, and I've specifically said so; but I find that a repeating of the above information is not helpful to the questions being asked.

YMMV

Brad

[Walt & Vicki]

I have a 2015 Ram 3500 DRW, and yes it will alert you of low tire pressures. As for lowering tire psi in the front of a diesel pickup, there is no reason unless you do want to abuse your tires. Lower pressure on the loaded front tire creates heat build-up period, no doubt or question about it. Rear pressure is much more forgiving when lowering pressure, but I personally see no point. If you are driving in snow, lower the pressure, but see no other reason to lower pressure. And knowing that if I ever have the need to put 6400lbs in the bed of my truck, I would hate to think I had to air my tires up to do so. It's a truck. Expect it to ride like a truck. I put air springs on the rear to make the loaded ride much better, can adjust to my liking in motion for different roads that are traveled. The door placard is there for a reason. Just my 2 cents, but, to each his/her own.

[Carl n Susan]

Originally Posted by kowbra

...Point is, for your F350, I would have expected similar to my RAM 3500 - it has the sensors, and an area in the display to check the tires, but it will not trigger any warnings.

Likely 60psi instead of 80psi in the rear tires will make for a much softer ride when empty, and could be the happy medium for you....

Brad

Ford's setup for 2015 F350 has a tire pressure sensor in each wheel. If the pressure in the rear drops below 60 it throws an Alert on the LCD screen and illuminates a little icon. The part that bugs me is Ford knows which sensor is alarming, but they don't identify it. It is up to you to check each wheel's pressure to find the deviant one. The F30 duallys don't have a tire pressure system in 2015 (and later up to around 2019?).


Empty, my rear wheels scale at 3,200 lbs. I suspect 50 PSI has enough weight capacity for that load and a much softer ride. But 60 works and it is better than 80.



And the claim that you have to run the tires at the pressure listed on the door pillar is just plain old bogus.

[Walt & Vicki]

Mine will actually show you the six wheel display and tell you which tire is low. Would have thought the Ford would have done the same.

[kowbra]

Originally Posted by Walt & Vicki

I have a 2015 Ram 3500 DRW, and yes it will alert you of low tire pressures. As for lowering tire psi in the front of a diesel pickup, there is no reason unless you do want to abuse your tires. Lower pressure on the loaded front tire creates heat build-up period, no doubt or question about it. Rear pressure is much more forgiving when lowering pressure, but I personally see no point. If you are driving in snow, lower the pressure, but see no other reason to lower pressure. And knowing that if I ever have the need to put 6400lbs in the bed of my truck, I would hate to think I had to air my tires up to do so. It's a truck. Expect it to ride like a truck. I put air springs on the rear to make the loaded ride much better, can adjust to my liking in motion for different roads that are traveled. The door placard is there for a reason. Just my 2 cents, but, to each his/her own.

Yes, I think you make a good point, Walt
On DRWs it is a lot more effort to air up and down, and with the extra tires and weight when empty it means it doesn't make as much of a difference. I've done the same as you with my DRWs.

And for 2500 class, where often the placard recommends lower pressures all around (such as 65psi on newer RAM 2500s), the ride quality is often very good, whether empty or loaded, lower pressure or higher.

The class that often will see a dramatic difference is the 3500 class SWRs. The empty ride with 80psi is often very harsh on any small, sharp bumps; such as washboard, frost heaves or concrete cracks on freeways. I believe this is the group that often considers airing down and up for ride quality.

These are work trucks, and I love that they don't ride like a half ton. But when the rear axle is literally leaving the ground on sharp bumps, and you feel like a kidney punch when it does, sometimes it makes sense to do something about it.
One example is when I go to the farm; at 80psi in the rear when empty, and on the washboard gravel, the truck will dangerously skate back and forth at anything over 30-40mph. I air down on the rear tires and can drive 50mph smoothly and safely.

Of course, then there is the whole off road group as well; but I'm not sure how many of those are on this forum. Let's just say, the off road group does not pay attention to the government regulations on how much air the manufacturer say to put in the tires. They would literally not be able to drive to where they do with full tire pressures.

There are the regulations, then there are those situations where those regulations prevent the vehicle from safely doing the job at hand; in fact, as I've pointed out, there are cases where it is more dangerous to follow the regulations (as they exist arbitrarily today).

I've made my decision, which applies to my situation. I not only support others making a different decision for their situation, but I encourage it; and I have provided information to help all of us to make an informed choice. Following the manufacturer placard works for most situations, but not for all.

JMHO, and YMMV and all that

Brad

[Walt & Vicki]

Exactly. to each his own. That's why the snow comment was in there. Also know about going off road as I grew up building Jeeps, K-5, Broncos, Cruisers and many other vehicles. The roads around the area I grew up were gravel and you occasionally got crush n run. If you drive that fast in a truck not set up for such roads, slow down, or get the tractor and yardbox and smooth it out. I do agree lowering tire pressure for extended times when not towing or hauling in SRW, but only on the rear axle and no more than 10% max pressure on the door placard. And there is a lot of valuable info in this thread, just have to swim through the fog an take it with a grain of salt.
Best,
Walt

[kowbra]

Originally Posted by Walt & Vicki

And there is a lot of valuable info in this thread, just have to swim through the fog an take it with a grain of salt.
Best,
Walt

LOL, best quote of the whole thread!

Brad