Tire pressure

[sheets7777]

I did try a search but couldn't really come to a conclusion. I run Nitto Trail Grapplers 35X11.5r20
Tire sidewall says max 80lbs currently have 65lbs. Have read this is too high for daily driver. I don't tow/ haul with it just play. Is 35lbs ok to drop to. 2016 Ram 1500.
Thanks,

 

[bm02tj]

Chalk the tread and drive a short distance
to check but 35lb should be good with truck empty
you are looking for even chalk removal

 

[sheets7777]

Yeah read about the chalk test, thanks. I ran 35 Grabbers on my last and 35lbs was ok but it was considerably lighter. I was checking the wifes and of course thought now I'll check mine was expecting 35/40 but they set them @ 65lbs when they rotated them. Just seems high but looking at max I didn't want to just drop them without asking. Plus Burla said I needed a new mechanic anyway Haha.

 

[michael harpe]

Discount tire is setting my milestar par9gnia m/t 37x12.5x20 at 50psi. It's a 14 ply tire though so might be stiffer than yours. The tires max psi is 90. They said it would pretty much be undrivable at that point.

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[huntergreen]

I have Cooper at3, I run them at 40#.

 

[Tim Garceau]

Discount tire is setting my milestar par9gnia m/t 37x12.5x20 at 50psi. It's a 14 ply tire though so might be stiffer than yours. The tires max psi is 90. They said it would pretty much be undrivable at that point.

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We’re talking about tires in here, not bricks of lead.

39 psi is right on the door.

 

[michael harpe]

We’re talking about tires in here, not bricks of lead.

39 psi on the door.

So am I. Please explain to the back of the class your lead comment. I was passing notes. [emoji851][emoji1812]

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[Tim Garceau]

80 lbs a tire might be heavier than Pb!

 

[ram1500rsm]

Ran 34 psi in my Falken AT3W 315/70/17 and now I run 30psi in my KO2 37x12.5x17’s
You can relax the psi a little more on the 17” sizes according to the TRA load index tables.

If you want to keep the same loading rating with a 35x11.5x20 LT tire according to what you have in your door sticker you want around 50psi. At 35psi the same tire will offer 2040 lbs support. Your GAWR rear or front is 3900 lbs so technically all you need is a tire able to support 1950lbs at each corner.

 

[Graygoose]

Nitto Ridge Grappler, 35x12.50x20...run about 42-44#.

 

[sheets7777]

Dropped to 45psi I'll see how that does for now. Thanks for the replies.

 

[michael harpe]

80 lbs a tire might be heavier than Pb!

Well if I was a laden swallow then you'd run 80-90psi. But an unladen swallow would require less. However if it's an African or european swallow would change things too. [emoji851]

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[CincyZach]

Here is a thread with some info for you.

Tires opinion

 

[Litos]

I just got done reading 4 different tire pressure links that say 65psi is the Max tire psi for Nitto LT325/50/22 122S...

my TPMS light came on and it says I had 31, 34, 32 and 33...

It doesn't matter which tire has what PSI, I was just more concerned seeing I was WAAAYYYY OFF the recommended PSI for this sized tire...

I think tomorrow, I'll do 50psi on all 4 corners...

thoughts ??

 

[jhgee]

Chalk the tread and drive a short distance
to check but 35lb should be good with truck empty
you are looking for even chalk removal

That’s an awesome idea…thanks…I’m running 37X12X20 Dealer set to 44

 

[Shawn Burns]

The model of RAM that you own can factor in to what pressure is supposed to be in the tires. My Rebel calls for 55f and 45r, where a big horn calls for much lower psi.

 

[atreides]

Chalk test is king. Easiest way to ensure you've got the right pressure.

To get a decent starting point for PSI:
1. Find the gross vehicle weight per corner: GAWR / 2 = Weight Per Corner
2. Find the max weight rating of your current tires: this is written on the side wall.
3. Find the ratio of weight per corner to max weight rating of your tires: Weight Per Corner / Max Weight Rating = Ratio. This number should be a decimal that is less than 1.0.
4. Multiply the tire's max PSI @ max weight (found on sidewall) by the ratio from step 3: Ratio * Max PSI = PSI. This is the PSI you should start with.

An example using completely made up numbers:
GAWR (Gross Axle Weight Rating) = 5,000 lbs
GAWR / 2 = 2,500 lbs
Tire max PSI and weight: 4,269 lbs @ 69 PSI
Gross corner weight / Tire max weight = ratio: 2,500 / 4,269 = 0.59
Ratio * Tire max PSI = PSI: 0.59 * 69 = 41 PSI

In this made up hypothetical example case, you can start with 41 PSI and add or remove pressure to get the ride and tire wear you want. Note that our trucks and most others will have a different GAWR for the front and rear.