Lowering PSI

[2500ltd]

Hi!

My 2500 is mainly my tow vehicle for my Airstream.

On smooth roads, it rides super stable with trailer in tow. On bumpy roads, it’s another story. Want to make it a bit less rough riding.

Right now, I’m running the Transforce AT tires at 65 as per the sticker. Want to go to 50 front and 55 back. According to the Firestone load chart, the tires could support a total of 10750 lbs at those inflation levels. Fully loaded including tongue weight, my vehicle weight is around 9500 lbs.

My question: Is this cutting it too close?

Thanks in advance for the input.

 

[AH64ID]

What are your axle weights?

 

[H3LZSN1P3R]

Hi!

My 2500 is mainly my tow vehicle for my Airstream.

On smooth roads, it rides super stable with trailer in tow. On bumpy roads, it’s another story. Want to make it a bit less rough riding.

Right now, I’m running the Transforce AT tires at 65 as per the sticker. Want to go to 50 front and 55 back. According to the Firestone load chart, the tires could support a total of 10750 lbs at those inflation levels. Fully loaded including tongue weight, my vehicle weight is around 9500 lbs.

My question: Is this cutting it too close?

Thanks in advance for the input.

Total vehicle weight means nothing you need to know what the weights are for the front axle and rear axle separately.
Also you should at least start by telling us what engine
4WD or not
what body config RCLB,CCSB,CCLB, or MCSB.
Trim level
And the tongue weight on the trailer

With all that info we can figure out roughly what your weights should be front and rear

 

[2500ltd]

Total vehicle weight means nothing you need to know what the weights are for the front axle and rear axle separately.
Also you should at least start by telling us what engine
4WD or not
what body config RCLB,CCSB,CCLB, or MCSB.
Trim level
And the tongue weight on the trailer

With all that info we can figure out roughly what your weights should be front and rear

Yes, for sure. Here goes:

My front axle weight is at 4675 and rear 4960
I’ve got a Cummins and it’s 4x4
Limited Trim, 2021 model year
Tongue weight is 950 but the axle numbers above include it, weight distributed with my Equalizer hitch

Sorry, not sure what you mean by body config.

Thanks for the help!

 

[AH64ID]

Yes, for sure. Here goes:

My front axle weight is at 4675 and rear 4960
I’ve got a Cummins and it’s 4x4
Limited Trim, 2021 model year
Tongue weight is 950 but the axle numbers above include it, weight distributed with my Equalizer hitch

Sorry, not sure what you mean by body config.

Thanks for the help!

That front axle weight seems off by 1K lbs, or you either have more tongue weight than you think or not enough tension on the WDH.

Body config is cab/bed. So mine is a CC LB (Crew Cab Long Bed).

 

[H3LZSN1P3R]

Looks like 45 front and 50 rear would be good for your axle weights.

RC= Regular cab
CC= Crew cab
MC= Mega cab
SB= Short box
LB= Long box

 

[2500ltd]

Looks like 45 front and 50 rear would be good for your axle weights.

RC= Regular cab
CC= Crew cab
MC= Mega cab
SB= Short box
LB= Long box

Thanks. This is helpful.

 

[2500ltd]

That front axle weight seems off by 1K lbs, or you either have more tongue weight than you think or not enough tension on the WDH.

Body config is cab/bed. So mine is a CC LB (Crew Cab Long Bed).

Thanks. Tongue weight is for sure 950. Measured several times through different methods. Once I’ve played around with tire pressure a bit more, I may adjust the Equalizer but off by a thousand you think? The front axle should be heavier than the back, and by that much?

 

[AH64ID]

Thanks. Tongue weight is for sure 950. Measured several times through different methods. Once I’ve played around with tire pressure a bit more, I may adjust the Equalizer but off by a thousand you think? The front axle should be heavier than the back, and by that much?

4765 is quite light for a Cummins pickup. The lowest I’ve had my 22 is 5120 with a 7000lb stock trailer and no WDH. Tongue weight around 1000lbs.

You haven’t said if you have a short or long bed, but empty weight should be around 5K.

I wouldn’t air the fronts down to match that weight, because your weight will go up when you disconnect the trailer. I’d use enough air for 5200lbs at a minimum. So 50/50 is the lowest I’d run, and probably 55/50 for towing with those weights.

 

[2500ltd]

4765 is quite light for a Cummins pickup. The lowest I’ve had my 22 is 5120 with a 7000lb stock trailer and no WDH. Tongue weight around 1000lbs.

You haven’t said if you have a short or long bed, but empty weight should be around 5K.

I wouldn’t air the fronts down to match that weight, because your weight will go up when you disconnect the trailer. I’d use enough air for 5200lbs at a minimum. So 50/50 is the lowest I’d run, and probably 55/50 for towing with those weights.

Helpful, tx. It’s a short bed. And you need 50 front, 55 rear correct?

 

[AH64ID]

F/R, do 55 front and 50 rear is what I would run at the weights you posted.

 

[2500ltd]

F/R, do 55 front and 50 rear is what I would run at the weights you posted.

Given there’s more weight on the back, should it not be the reverse?

 

[AH64ID]

Given there’s more weight on the back, should it not be the reverse?

The front pressure is based off the low weight, and it likely increasing when you take the trailer off as well as steering feel. You wouldn’t want to have to increase pressure while camping just from unhooking the trailer.

 

[Will_T]

4765 is quite light for a Cummins pickup. The lowest I’ve had my 22 is 5120 with a 7000lb stock trailer and no WDH. Tongue weight around 1000lbs.

With my truck with an ~8,200 lb. trailer with 950 lb. tongue and WD hitch my front is typically about 4,750 and rear about 5,300. I do have a canopy on it and usually quite a bit of weight in the bed. Someday I should weigh the axles with the truck empty. But it is never empty.

Edit: Just looked and the one weighing I have with the TT before the canopy was 4,800 front and 5,000 rear. I may have had a little less weight in the bed that time.

 

[AH64ID]

With my truck with an ~8,200 lb. trailer with 950 lb. tongue and WD hitch my front is typically about 4,750 and rear about 5,300. I do have a canopy on it and usually quite a bit of weight in the bed. Someday I should weigh the axles with the truck empty. But it is never empty.

Edit: Just looked and the one weighing I have with the TT before the canopy was 4,800 front and 5,000 rear. I may have had a little less weight in the bed that time.

Interesting, I’ve never come close to that light on all 3 of my CTD’s. I got close once with 1200+ TW and a bed full of weight behind the axle on the 05.

 

[jsalbre]

Interesting, I’ve never come close to that light on all 3 of my CTD’s. I got close once with 1200+ TW and a bed full of weight behind the axle on the 05.

Could it be that all of your trucks have been long beds? That rear axle being almost 2' further back puts a lot more of the cab weight on the front axle.

 

[AH64ID]

Could it be that all of your trucks have been long beds? That rear axle being almost 2' further back puts a lot more of the cab weight on the front axle.

They have, I didn’t think it would make that much of a difference but looking at the tow chart the difference in the bed length and transmission would about do it on an empty truck.

Good call.

 

[2500ltd]

The front pressure is based off the low weight, and it likely increasing when you take the trailer off as well as steering feel. You wouldn’t want to have to increase pressure while camping just from unhooking the trailer.

Thanks. Lowered front to 55 and rear to 50. Quite please with handling and ride now.

Question. Is AlphaOBD the only way to get rid of the resulting low pressure warning? Do dealers normally accept to modify the threshold?

 

[2500ltd]

To continue on the axle weight ratings theme, here’s mine (21 Cummins Limited, 6.4 bed) with the truck on a half tank and all cargo removed:

F 4960
R 3748

 

[cj8rockcrawler]

Thanks. Lowered front to 55 and rear to 50. Quite please with handling and ride now.

Question. Is AlphaOBD the only way to get rid of the resulting low pressure warning? Do dealers normally accept to modify the threshold?

A 3500 will also get rid of it.

I believe on the 2500 you can't get rid of it only change the set psi to trigger the warning.