Tire pressure?

[rhagfo]

Originally Posted by sourdough

Looks like Ram has changed their minds on recommended pressures for the new HD trucks. Since my '14 they've been 65/80 which was too high for an empty truck; looks like they've gotten more reasonable.

Your sticker of 60/65 will be just fine for an empty truck. When you drop that trailer on there the truck is going to be stretched weight wise so for sure air those rear tires up to 80psi. I would put 65 in the front but 60 would probably work if you find it more comfortable.

I'm glad you got the 4.10 rear, that truck needs it with that trailer. The 8 speed will make it much better as well.

Well not so, the tire loading placard is for a axle loaded to it's maximum weight. The tires on the label have a load rating of 3,638# ea. total 7,276, likely on a rear axle rating of 6,000#. That is why the rear inflation is only 65 psi.

Our DRW with 17" tires and a rear axle rating of 9,750#, only calls for 65 psi at that weight, I don't weigh that much on the rear axle loaded so run about 55 psi for better ride and tire wear.

Just like running too low an air pressure, running too high for the load will change the wear pattern.

[Pathman]

Originally Posted by rhagfo

Well not so, the tire loading placard is for a axle loaded to it's maximum weight. The tires on the label have a load rating of 3,638# ea. total 7,276, likely on a rear axle rating of 6,000#. That is why the rear inflation is only 65 psi.

Our DRW with 17" tires and a rear axle rating of 9,750#, only calls for 65 psi at that weight, I don't weigh that much on the rear axle loaded so run about 55 psi for better ride and tire wear.

Just like running too low an air pressure, running too high for the load will change the wear pattern.

So, you’re saying that the max is 65psi that is stated on the label and not on the sidewall?
I thought I had this figured out with the input of the others, but now I’m uncertain.
So then if I’m understanding you correctly, you’d never go above the psi on the label, but you would air down your psi unless the truck was loaded to the max?

[JRTJH]

Originally Posted by Pathman

So, you’re saying that the max is 65psi that is stated on the label and not on the sidewall?
I thought I had this figured out with the input of the others, but now I’m uncertain.
So then if I’m understanding you correctly, you’d never go above the psi on the label, but you would air down your psi unless the truck was loaded to the max?

On my Ford, the tire pressure label instructs that the maximum cargo is XXXX. The tire size and the operating pressure recommended is the pressure required to operate the truck at that payload capacity (which is the truck GVWR).

Here is the statement from the Ford Owner's Manual:

Note: Do not reduce tire pressure
to change the ride characteristics
of the vehicle. If you do not
maintain the inflation pressure at
the levels specified by Ford, your
vehicle may experience a condition
known as shimmy. Shimmy is a
severe vibration and oscillation in
the steering wheel after the vehicle
travels over a bump or dip in the
road that does not dampen out by
itself. Shimmy may result from
significant under-inflation of the
tires, improper tires (load range,
size, or type), or vehicle
modifications such as lift-kits. In
the event that your vehicle
experiences shimmy, you should
slowly reduce speed by either lifting
off the accelerator pedal or lightly
applying the brakes. The shimmy
will cease as the vehicle speed
decreases.
Maximum Inflation Pressure is
the tire manufacturer's maximum
permissible pressure and the
pressure at which the maximum
load can be carried by the tire. This
pressure is normally higher than
the manufacturer’s recommended
cold inflation pressure which can
be found on the Safety
Compliance Certification Label
(affixed to either the door hinge
pillar, door-latch post, or the door
edge that meets the door-latch
post, next to the driver's seating
position), or Tire Label located on
the B-pillar or the edge of the
driver's door. The cold inflation
pressure should never be set lower
than the recommended pressure
on the Safety Compliance
Certification Label or Tire Label.

So the tire pressure recommendations on the label are for operating the truck "at GVWR" which is fully loaded. With the diesel, I haven't found any reason to reduce the front axle pressure below the recommended label setting and I don't have any "rough ride when the truck is empty" so I leave the rear axle tire pressure at the label setting for the rear axle also.

It's the same with my DW's Edge. We run the tires "at the label recommendation pressure" and find that works for even tire wear, good overall performance and no loss of traction in wet/snow conditions.

My tires on the truck have a "sidewall pressure maximum 80 PSI" but I've never run them above the label recommendation and I've always had even tire tread wear.

Here is a photo of a Ford "payload sticker" (not my truck) with the comment to see the owner's manual for explanation. In the owner's manual is where you find the above comments and a significantly longer explanation of how to set tire pressure. Bottom line, Ford recommends following the decal recommendations for a truck at GVWR (max payload) and the further recommend not to reduce pressure when operating the truck because of potential handling probems. Maybe it's a CYA for Ford, but I've never had problems just setting the pressure to the label recommendation and keeping it there. YMMV

[bsmith0404]

I find all the differences in opinions interesting. What John just explained is correct. The psi listed on the door sticker is what is required for the tire to carry the max weight for the GVWR and Axle rating for your truck. The max psi listed on the sidewall of the tire is what is required to carry the max weight the tire is rated for. Less psi mean less load carrying capacity for the tire, however if the loads placed on the tire do not exceed the weight ratings of the truck, max psi is not required. That is why I adjust my tire pressure based on what I’m towing/how much weight is being placed on the tire.

Now if you ask this same question about your trailer tires, most on here will tell you upgrade your tires to a heavier load range and always run max psi. That doesn’t follow the same logic that was just discussed above. I have LRG tires on my 5th wheel which have way more weight carrying capacity than what is required. They have a max psi of 110, I run 95 in them. Which, based on the manufacturer inflation chart of psi vs load, is still way more than needed.

Basically, every tire has a max weight at xx psi rating. If less weight is being placed on that tire, less air is required to carry that weight. Some of us will adjust psi accordingly, others just always run max. Which method you choose to use is up to you.

[wiredgeorge]

John, this is good info except for when the owner of a 1/2 ton with P rated tires swaps those tire for LT. Then if the owner follows the payload placard settings, the LT tires' heavier load capacity won't be utilized. Am I wrong?

[Pathman]

Originally Posted by JRTJH

On my Ford, the tire pressure label instructs that the maximum cargo is XXXX. The tire size and the operating pressure recommended is the pressure required to operate the truck at that payload capacity (which is the truck GVWR).

Here is the statement from the Ford Owner's Manual:

Note: Do not reduce tire pressure
to change the ride characteristics
of the vehicle. If you do not
maintain the inflation pressure at
the levels specified by Ford, your
vehicle may experience a condition
known as shimmy. Shimmy is a
severe vibration and oscillation in
the steering wheel after the vehicle
travels over a bump or dip in the
road that does not dampen out by
itself. Shimmy may result from
significant under-inflation of the
tires, improper tires (load range,
size, or type), or vehicle
modifications such as lift-kits. In
the event that your vehicle
experiences shimmy, you should
slowly reduce speed by either lifting
off the accelerator pedal or lightly
applying the brakes. The shimmy
will cease as the vehicle speed
decreases.
Maximum Inflation Pressure is
the tire manufacturer's maximum
permissible pressure and the
pressure at which the maximum
load can be carried by the tire. This
pressure is normally higher than
the manufacturer’s recommended
cold inflation pressure which can
be found on the Safety
Compliance Certification Label
(affixed to either the door hinge
pillar, door-latch post, or the door
edge that meets the door-latch
post, next to the driver's seating
position), or Tire Label located on
the B-pillar or the edge of the
driver's door. The cold inflation
pressure should never be set lower
than the recommended pressure
on the Safety Compliance
Certification Label or Tire Label.

So the tire pressure recommendations on the label are for operating the truck "at GVWR" which is fully loaded. With the diesel, I haven't found any reason to reduce the front axle pressure below the recommended label setting and I don't have any "rough ride when the truck is empty" so I leave the rear axle tire pressure at the label setting for the rear axle also.

It's the same with my DW's Edge. We run the tires "at the label recommendation pressure" and find that works for even tire wear, good overall performance and no loss of traction in wet/snow conditions.

My tires on the truck have a "sidewall pressure maximum 80 PSI" but I've never run them above the label recommendation and I've always had even tire tread wear.

Here is a photo of a Ford "payload sticker" (not my truck) with the comment to see the owner's manual for explanation. In the owner's manual is where you find the above comments and a significantly longer explanation of how to set tire pressure. Bottom line, Ford recommends following the decal recommendations for a truck at GVWR (max payload) and the further recommend not to reduce pressure when operating the truck because of potential handling probems. Maybe it's a CYA for Ford, but I've never had problems just setting the pressure to the label recommendation and keeping it there. YMMV

Ok, so if the “label” psi is the recommended psi for GVWR, and the manufacturer is also saying don’t ever lower the psi below the psi on the label, that would mean that the label psi covers the truck weight from empty to fully loaded, is that accurate?

[rhagfo]

Originally Posted by bsmith0404

I find all the differences in opinions interesting. What John just explained is correct. The psi listed on the door sticker is what is required for the tire to carry the max weight for the GVWR and Axle rating for your truck. The max psi listed on the sidewall of the tire is what is required to carry the max weight the tire is rated for. Less psi mean less load carrying capacity for the tire, however if the loads placed on the tire do not exceed the weight ratings of the truck, max psi is not required. That is why I adjust my tire pressure based on what I’m towing/how much weight is being placed on the tire.

Now if you ask this same question about your trailer tires, most on here will tell you upgrade your tires to a heavier load range and always run max psi. That doesn’t follow the same logic that was just discussed above. I have LRG tires on my 5th wheel which have way more weight carrying capacity than what is required. They have a max psi of 110, I run 95 in them. Which, based on the manufacturer inflation chart of psi vs load, is still way more than needed.

Basically, every tire has a max weight at xx psi rating. If less weight is being placed on that tire, less air is required to carry that weight. Some of us will adjust psi accordingly, others just always run max. Which method you choose to use is up to you.

So keep in mind that if you inflate a tire to the sidewall maximum say 80 psi, and the load sticker states 65 psi for max payload, you are technically over inflating the tire. So in reality the tire profile will look like the over inflated tire in the picture.

[JRTJH]

Originally Posted by Pathman

Ok, so if the “label” psi is the recommended psi for GVWR, and the manufacturer is also saying don’t ever lower the psi below the psi on the label, that would mean that the label psi covers the truck weight from empty to fully loaded, is that accurate?

Yep, that's the "simplify it for all the dummies in the world" approach that all the auto manufacturers have taken over the past 10 years or so. Used to be different, but then the Model T owner's manual has a section on replacing the head gasket, so things have been "simplified more than just a little" over the years.

[Pathman]

So after George’s comments, that really cleared things up for me ��*♂️�� LOL.

This is almost right up there with the pin weight calculations!
Tire PSI is a bit worse I think, I think this stuff shouldn’t be subjective. There should be simple empirical data that determines weights, psi, etc., the calculations shouldn’t be based on opinions don’t you think?

Thanks all for your comments and info. I’ll check my truck manual later and see what Ram says about tire pressure.
On top of this, I’ll have to deal with the service guys at the dealership and what they feel is the right psi that they put in the trailers tires when I pick it up! UGH!

[JRTJH]

Originally Posted by wiredgeorge

John, this is good info except for when the owner of a 1/2 ton with P rated tires swaps those tire for LT. Then if the owner follows the payload placard settings, the LT tires' heavier load capacity won't be utilized. Am I wrong?

George, that decal specifically addresses the tire size/type (LT 275 65R18 LRE) and on a half ton, it does the same (P255 70R18) and gives specific pressure requirements. If the owner changes tire size, then that label no longer applies and the owner is responsible for adjusting pressure to the appropriate settings for the new tires. I've never seen a "conversion chart for tire types/sizes/pressure recommendations" in any vehicle owner's manual...

I guess it's "uncharted territory" as far as the owner's manual and the tire/payload decal.

[JRTJH]

Originally Posted by Pathman

So after George’s comments, that really cleared things up for me ��*♂️�� LOL.

This is almost right up there with the pin weight calculations!
Tire PSI is a bit worse I think, I’m that this stuff shouldn’t be subjective. There should be simple empirical data that determines weights, psi, etc., the calculations shouldn’t be based on opinions don’t you think?

Thanks all for your comments and info. I’ll check my truck manual later and see what Ram says about tire pressure.
On top of this, I’ll have to deal with the service guys at the dealership and what they feel is the right psi that they put in the trailers tires when I pick it up! UGH!

If the "service guys at the dealership" adjust the trailer tire pressure to anything different from the tire pressure label that's located on the trailer roadside front corner, then they aren't following "federal guidelines"... It's the trailer manufacturer (Keystone) that establishes correct tire type, size and operating pressure, not some guy in a blue shirt at a dealership.....

[travelin texans]

This topic ALWAYS gets WAY over complicated!
Use the pressures on the placard of your vehicle & quit overthinking it! If the tire looks low when you hook up the rv add air!
DONE!

[Pathman]

Well, I think we’re all “dummies” when starting out JR, otherwise we wouldn’t be on here asking questions of you seasoned veterans, but no need for name calling!LOL

[Pathman]

Originally Posted by JRTJH

If the "service guys at the dealership" adjust the trailer tire pressure to anything different from the tire pressure label that's located on the trailer roadside front corner, then they aren't following "federal guidelines"... It's the trailer manufacturer (Keystone) that establishes correct tire type, size and operating pressure, not some guy in a blue shirt at a dealership.....

Copy that, thanks JR.

[Pathman]

Originally Posted by travelin texans

This topic ALWAYS gets WAY over complicated!
Use the pressures on the placard of your vehicle & quit overthinking it! If the tire looks low when you hook up the rv add air!
DONE!

I know you’re speaking to everyone in general Texas, but I wasn’t overthinking it till the various responses started coming in!LOL

However, your response kinda puts me right back where I started, which is, so you leave the psi where it is, or raise it when towing?
I don’t think a visual inspection of tire pressure is the right way to go.

[JRTJH]

Originally Posted by Pathman

Well, I think we’re all “dummies” when starting out JR, otherwise we wouldn’t be on here asking questions of you seasoned veterans, but no need for name calling!LOL

Definitely not "name calling"... But the reality is that over the years, all the manufacturers have "dumbed down the manuals", replaced gauges with idiot lights, reduced thinking and making decisions to a "yes/no" or "pass/fail" condition because, it seems, people no longer want to take the time to study and understand the "why" and make "reasoned decisions"... They'd (we) would rather have someone else just tell us if it's OK or not and get back to our i-phones or busting bubbles on a tablet game..... Not being cynical, just my observation about how our society has evolved from back when every kid took shop class and knew how to grease wheel bearings on Dad's old car to today when that's been replaced with a "mandatory typing class" so kids can access the internet (probably to find those bubble popping games).....

[wiredgeorge]

Danny doesn't currently own a truck because he relied on the eyeball method for inflating his tires and they all blew up and there is no good way to deal with four blown tires (I think).

[JRTJH]

Originally Posted by JRTJH

If the "service guys at the dealership" adjust the trailer tire pressure to anything different from the tire pressure label that's located on the trailer roadside front corner, then they aren't following "federal guidelines"... It's the trailer manufacturer (Keystone) that establishes correct tire type, size and operating pressure, not some guy in a blue shirt at a dealership.....

Originally Posted by Pathman

Copy that, thanks JR.

Incidentally, I don't think I've seen a Keystone trailer of any brand, in the past 5 or 6 years (since the new RVIA tire reserve capacity guidelines took effect), that has any recommended pressure other than the tire sidewall max. On LRC tires, that's 50PSI, on LRD tires it's 65PSI, on LRE tires it's 80PSI, on LRF it's 95PSI and on LRG it's 110 PSI.

So, essentially, I'd suspect that the tire size/pressure decal on the trailer will be the same as the tire sidewall maximum inflation pressure.... That's Keystone's way of managing the smallest tire (cheapest in most cases) to get the maximum load carrying capacity. They seldom would chooses a larger tire (costs more to install) to lower the pressure when they can install a smaller tire (costs less) and run it at maximum sidewall pressure to achieve the same "load carrying capacity reserves" mandated by RVIA.

sort of like choosing a 30 amp trailer electrical input system over a 50 amp system when the 30 amp will operate the systems included as OEM. If the owner want's a second air conditioner, on a small trailer, "that's their problem, not Keystone's"

For most manufacturers, they're in the business to make money, not to provide a service to the public. If they're not making the shareholders enough profit, something changes or they go out of business when the shareholders sell off their "non productive stock portfolio".... It's "do or die" and in the RV world, it's all about the profit. Build what sells as cheaply as posssible to maximize the shareholder's stock increases.

Might be sad to realize that, but .....

[travelin texans]

Originally Posted by wiredgeorge

Danny doesn't currently own a truck because he relied on the eyeball method for inflating his tires and they all blew up and there is no good way to deal with four blown tires (I think).

Actually in 300+k miles 10+ years full-time towing a 16.5k lb 5th wheel I used the placard inflation pressures for the truck & the inflation for max on the sidewall of whatever size tire were on the rv at any given time, never an issue with any tires in that 300+k miles.
I did weigh the setup at each individual wheel location a couple of times & several times truck & rv separately, but with all those weights I never changed the inflation rates on any tire & was always within the limits of each tire & all other weights of truck & rv.
I would rather run any tire a bit over inflated rather than under. Under inflation causes heat which is very detrimental to tires as well as causing drag lowering fuel mileage & causing handling issues with squirmy tires.
I would never run any tire below the placard inflation recommendations or above the inflation imprinted on the sidewall of the tire, with these 2 pressures there's about 10-15 lb spread that should work for any tire, loaded or unloaded.
Pathman, Other than my experiences here I don't know how to help you further understand!

[Pathman]

Originally Posted by travelin texans

Actually in 300+k miles 10+ years full-time towing a 16.5k lb 5th wheel I used the placard inflation pressures for the truck & the inflation for max on the sidewall of whatever size tire were on the rv at any given time, never an issue with any tires in that 300+k miles.
I did weigh the setup at each individual wheel location a couple of times & several times truck & rv separately, but with all those weights I never changed the inflation rates on any tire & was always within the limits of each tire & all other weights of truck & rv.
I would rather run any tire a bit over inflated rather than under. Under inflation causes heat which is very detrimental to tires as well as causing drag lowering fuel mileage & causing handling issues with squirmy tires.
I would never run any tire below the placard inflation recommendations or above the inflation imprinted on the sidewall of the tire, with these 2 pressures there's about 10-15 lb spread that should work for any tire, loaded or unloaded.
Pathman, Other than my experiences here I don't know how to help you further understand!

I appreciate your insight Texas, but it’s not a matter of me understanding, I understood each of the 5-6 various responses, but determining which one to use is the issue, not understanding.

Your “2 pressures 10-15 lb spread” is likely the way I’ll approach psi.
The varied opinions regarding dropping psi etc., was confusing the matter, but that’s fine, I understand everyone has a different perspective.

Thanks again all, and please keep in mind, I’m from NJ, so “wisecracking” is a way of life up here, it’s not meant to be offensive in any way.