Tire Pressures

[GBBrown]

Curious why door jamb recommends 60# in front tires and 80# in the rear. All the weight when empty is in the front. Also tire manufactures recommend running full inflation on tires. Doesn't make sense to me.

 

[Ram4Sam]

Curious why door jamb recommends 60# in front tires and 80# in the rear. All the weight when empty is in the front. Also tire manufactures recommend running full inflation on tires. Doesn't make sense to me.

It doesn't make sense.....I think that is the lawyers talking. Unloaded, I run 65 in front and 55 in the back and am getting a good wear pattern, and a reasonable ride comfort wise, IMHO.......

Sam

 

[Bill Stockard]

It could be the tire pressure necessary to carry the max GVW rating load shown on the door jamb tag.

Bill

 

[kthaxton]

It could be the tire pressure necessary to carry the max GVW rating load shown on the door jamb tag.

Bill

This.^^^^^

 

[Ram4Sam]

It could be the tire pressure necessary to carry the max GVW rating load shown on the door jamb tag.

Bill

60 lbs. for the front at max weight??

Sam

 

[Newsa]

See the attached pics of door jamb. My truck has the dual range TPMS system

 

[tony1461571]

Did you stand on your head to take this one. :--)

 

[Bob4x4]

The 15's don't have the light load option,probably a legal issue

 

[Badunit]

Another oddity is the exact same truck but with the 6.4 Hemi calls for 65 psi in front instead of 60. Same model, same trim level, etc., just the different engine and the stuff that comes with it. I don't see how that makes sense.

 

[jus2shy]

Odd that the Hemi calls for more pressure, the Cummins already weighs almost 1,000 lbs more with all the associated gear of a CTD. Personally, I wasn't getting enough wear in the middle of my tires on my front axle at 60psi. I'm running them at 70 psi to get more wear in the middle of the tire or at least even it out. I think 65 psi should be good on the front. Rears, I had more shoulder wear at 50 psi, so I'm bumping those up to 55 psi. I typically drive empty with occasional hauling.

 

[EcoDiesel]

The 15's don't have the light load option,probably a legal issue

I tried 65 psi in the rear and it helped the ride noticeably but the TPMS went into alert mode--very annoying! I experimented and could drop pressure only about 8 psi before alerts started. The dealer said they could reset the system for either unloaded or loaded pressures but not both. Just plain stupid. What the lawyers have done is create a no-win situation where we either endure a brutal ride unloaded at 80 psi--even dangerous with the back end bouncing around--or put up with distracting TPMS nanny alerts. This should be a user-selectable range in the EVIC because load, terrain and tires can vary widely.

 

[Cummins12V98]

Very thankful I don't have that BS on my 15 Dually! I run 80 front 40 rear solo and 60 rear loaded.

 

[Newsa]

Very thankful I don't have that BS on my 15 Dually! I run 80 front 40 rear solo and 60 rear loaded.

I thought standard TPMS was now the law.

 

[jus2shy]

I thought standard TPMS was now the law.

Only on vehicles at 10,000 GVWR or lower.

 

[Cummins12V98]

I thought standard TPMS was now the law.

I can look at what the tire pressures that are on each wheel but there are no bells and whistles screaming at me.

 

[Mingoglia]

I can look at what the tire pressures that are on each wheel but there are no bells and whistles screaming at me.

I kinda wish the system was similar to my 2008 Toyota. It has a button you hold when you start it up and it will set the pressure at whatever it's currently set at. Then the light will come on if the pressure fluctuates by 20%. This way you could set the tires at 80 or 40 and it's all relative to what the pressure is set at, not hard coded.

In my dually I of course have the same pressures, but I kinda wish bells did scream if it were to drop by a certain percent as I'm rarely sitting on the screen with the pressures. If you're towing at GVWR it would be really nice if there was a warning if say an inside tire were going flat without you knowing and without you looking at the tire pressure screen.

Mike

 

[gsbrockman]

I can look at what the tire pressures that are on each wheel but there are no bells and whistles screaming at me.

That's the difference between TPMS and TPIS.

 

[kthaxton]

Another oddity is the exact same truck but with the 6.4 Hemi calls for 65 psi in front instead of 60. Same model, same trim level, etc., just the different engine and the stuff that comes with it. I don't see how that makes sense.

Same factory tire size? If the Hemi tires were smaller, or even had a larger diameter rim and same tire outside diameter, they would have less volume which would account for a higher needed pressure.

 

[Badunit]

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[AH64ID]

Curious why door jamb recommends 60# in front tires and 80# in the rear.

It is based on the GAWR of the truck.

With a 275/70R18E 60 psi gives you 6,040lbs and 80 psi gives you 7,280. 75 psi is plenty (7,060) but Ram probably decided to go up a little more in case you are at GAWR at doing 80. It is much easier to get to the RAWR than the FAWR.

Also tire manufactures recommend running full inflation on tires. Doesn't make sense to me.

Actually they don't. There is a reason that tire manufacturers create and publish load and inflation tables. Tire manufacturers want you running the proper pressure for the load, not max sidewall pressure for any load. Over-inflated is bad for traction, tread life, and increases the chance tire failure due to road hazards.

This is what Toyo's table looks like and is going to be good for other tire makes of the same size/load/pressure ratings.


So why the difference between Ram (Ford too, and probably GM as well) and the tire manufacturers? What happens if you blow a tire from under-inflation and the truck's TPMS didn't alert you?? Simple, once lawyers are involved it becomes Ram's fault and not the drivers. So now the light load option is gone.

Another oddity is the exact same truck but with the 6.4 Hemi calls for 65 psi in front instead of 60. Same model, same trim level, etc., just the different engine and the stuff that comes with it. I don't see how that makes sense.

I would guess that the Hemi had 17's.

65 psi on a 265/70R17 gives you air for 5,820 which is just above the 5,500lb FAWR on a 4wd Hemi 3500.