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Discussion Starter #1
I have 37.13.50r22 nitto ridge grapplers.
Just purchased the truck recently already set up etc etc. currently front tires are set at 65 and rear at 75. I had them rotated and seems like it is worse in the rear now. I am assuming prior to rotation there was less air in the rear?

Can I run them at 65 like the front or less?
I don’t tow anything. Anyone else have the same set up just curious what I can run.

Thanks all!
 

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What truck?

You can run the tires at whatever pressure you like. On 2500’s it’ll trip the TPMS light if you go too low, 3500’s with TPIS don’t care. 2500 TPMS thresholds can be adjusted with AlfaOBD or similar.

75 is way too high for your tire size and no load— a chalk test can help you discern what is good unloaded.
 

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Discussion Starter #3
What truck?

You can run the tires at whatever pressure you like. On 2500’s it’ll trip the TPMS light if you go too low, 3500’s with TPIS don’t care. 2500 TPMS thresholds can be adjusted with AlfaOBD or similar.

75 is way too high for your tire size and no load— a chalk test can help you discern what is good unloaded.
2500

I believe the dealership from when the truck was first purchased used a AlphaOBD to adjust the sensors or whatever. I do t have any tpms lights on.

What is a chalk test?
Do you think 65is to high in the front also?
 

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2500

I believe the dealership from when the truck was first purchased used a AlphaOBD to adjust the sensors or whatever. I do t have any tpms lights on.

What is a chalk test?
Do you think 65is to high in the front also?
37’s I ran 55 front 45 rear.

The dealer may have adjusted the pressure but I highly doubt it. Threshold is probably 60# on the rear.

Chalk test is take some chalk and mark across the tire tread. Roll the truck back or forward and see what rubs off. Add or subtract pressure to make the chalk all wear off. Then you’re utilizing the tread efficiently.

Thresholds might need adjusting still to accommodate what the appropriate pressure is.
 

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I would guess around 60 front 50 rear, if you buy a tread depth gauge you can also just watch how they wear. I run 80 all around and fronts wear about perfect, rears wear a tiny bit more on the middle, but need 80 as I load it to max fairly often.
 

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If you aren’t getting any warning lights from the TPMS system, this is easy:

Have the PSI set on the high side, say 70. Load your truck with a normal, everyday load.

Find a big, flat open space, like a empty parking lot.

Park your truck.

Using the chalk, draw a single line across the tread.

Drive your truck in a straight line for 20-30 yards.

Get out and check the chalk marks. If it is worn off in the middle, lower the pressure a bit and do it again.

Ideally, you want that chalk line to wear evenly across the tread.


I have 35x12.5x20’s and run 55 front, 50 rear most of the time. Lots of highway driving.

Good luck.




Sent from my iPhone using Tapatalk
 

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I have 37.13.50r22 nitto ridge grapplers.
Just purchased the truck recently already set up etc etc. currently front tires are set at 65 and rear at 75. I had them rotated and seems like it is worse in the rear now. I am assuming prior to rotation there was less air in the rear?

Can I run them at 65 like the front or less?
I don’t tow anything. Anyone else have the same set up just curious what I can run.

Thanks all!
What size rims you running? 10", 12" ?? Are those what we would call 'flotation' tires? Seeing as how they're in inches instead of metric, I'm going to assume they are.

If so, then be careful on the air pressure until you get used to it. I usually keep my stockers on the low side for comfort and to help prevent the inevitable future rattles that come with owning a HD Truck. I hate rattles. Hate 'em.

But with flotation tires you gotta be mindful of the inherent weakness of the sidewalls (flexible by design) compared to metric sizes. They're not 'weak' per se, but they're not as stiff as the metric tires as a rule. It shows up mostly in the heat of summer on a highway for a longer period of time.

You're just gonna have to experiment until you find pressures that you like.

I'd start out with 60 front and 50 rear, unloaded. Go from there
 

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Lots of talk and "theories" get presented, but load/inflation charts don't lie and you don't need to chalk test and "start out here and see what you think" or any of that nonsense.

And for your truck, unloaded, from the chart using 5k on the front axle and 3k on the rear axle, 40-45 psi front and 25-30 psi rear is where you should be.
60-70psi in an empty HD pickup with that size of tire and no load is like blocking your springs so you don't have suspension. Very uncomfortable and not the right answer.
 

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Discussion Starter #9
Well boys,

I went ahead and lowered my air and now I get the low tire pressure light on the dash......and that’s annoying so I am going to air it back up until I get something to overwrite the tpms setting......frustrating!
 

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While the light is annoying, to each their own. I'd deal with an idiot light on the dash that I knew wasn't a problem, for a while, before driving a truck that rides like a buckboard when it doesn't need to.
 

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Well boys,

I went ahead and lowered my air and now I get the low tire pressure light on the dash......and that’s annoying so I am going to air it back up until I get something to overwrite the tpms setting......frustrating!
AlfaOBD is the easiest and doesn't cost much if you have a PC or Android device already.

While the light is annoying, to each their own. I'd deal with an idiot light on the dash that I knew wasn't a problem, for a while, before driving a truck that rides like a buckboard when it doesn't need to.
For me the ride has nothing to do with it, but is a nice bonus. Traction and even wear is what I was after.
 

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While the light is annoying, to each their own. I'd deal with an idiot light on the dash that I knew wasn't a problem, for a while, before driving a truck that rides like a buckboard when it doesn't need to.
I do the same thing. I'm wondering though if there will be any trouble having that stupid light on forever? Will the computer reach a point where it thinks there is an actual problem?
 

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I do the same thing. I'm wondering though if there will be any trouble having that stupid light on forever? Will the computer reach a point where it thinks there is an actual problem?
No, that light can stay on forever with no issues. The TPMS light is a government mandated warning light to let you know there is an issue with tires. It is only an alert light, has no input into ecm/pcm.

Lots of people run without the sensors anymore because as the batteries die, sometimes they can be pricey to replace.
 
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