Tire pressure

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larrymax

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I bought my 2014 Ram a year ago and it has Achilles Dessert Hawk XMT 35x12.50 r20's on it. I've never had tires or a truck this size but I noticed traction was a problem. Especially on wet roads. Just figured that's the way it was.

One day a few months ago, I got the tpms warning that one of my tires was low. I think it was around 67psi. Then I really looked at the tire and noticed the max cold pressure was 60psi. I had been driving around for a long time with tires inflated to 80psi.

I figured the person I bought it from must have inflated them to that to clear the warning when I bought it or they didn't know either. No idea. I took them down to 50 just to be safe. Traction is still a problem. It does ride a lot nicer like that though. I ignore the tpms warning now.

For the life of me, I can't find a definite answer on what they should be for daily driving, no towing or hauling.

I contacted the manufacturer and got this response

"We are in receipt of your inquiry. We are a wholesale tire distributor of multiple brands of tires, not a tire manufacturer, and we create dedicated websites for each of the brands of tires we distribute. The Achilles brand became part of our portfolio of private label brands when we took over the name, October 1st of 2023. Since then, we are in contact with manufacturers we work with for the production of the series of tires we now offer under this brand: Touring Sport A/S, Street Hawk Sport, Desert Hawk HT3, Desert Hawk AT3, and Rugged Hawk.

We do not have any information on any lines of Achilles tires sold in the past nor do we know who distributed them. We suggest you contact the seller of the tires as they may be able to direct you to their distributor for further assistance.

Having said that, please note that most tire manufacturers provide us only with the maximum psi a tire can hold, since the tire manufacturer will not know where the tire may be ultimately installed. Since a tire in a particular size can be installed in multiple applications, each with varying weights, it is up to the manufacturer of the application to provide you with their recommended psi for the optimum performance of the after-market tires. We apologize for any inconvenience."

So on a 2014 Ram 2500 6.4 crew cab 4x4 with a 8ft bed, is there a best guess on what the pressure should be with those tires for daily driving?
 

mrack

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Search tire chalk test on you tube, every truck and tire is different so you need to find the correct pressure for your truck specifically, that’s what the chalk test does.

Go with falken wildpeaks for your next set of tires and you’ll never worry about wet traction again. They stick to wet roads like glue.
 
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larrymax

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Thank you, I feel like an idiot. Should have known better. Just didn't occur to me. The tires still have a lot of tread left believe it or not. I live in Washington state so rain is an issue. I'd love to clear the stock tire tpms warning, but I've read that's another complicated issue.
 

rzr6-4

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When you get into the off-road tire world, you just have to experiment a little bit. I have 18 inch wheels but otherwise similar, I started out at 40 psi and even then it felt like it was floating on gravel. Now I run 33 upfront and 32 to 35 in the rear depending on if I’m towing. Being in the 60+ neighborhood on tires like that is wild, I’m sure it road like trash and you probably already have some bad wear patterns.
 
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larrymax

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When you get into the off-road tire world, you just have to experiment a little bit. I have 18 inch wheels but otherwise similar, I started out at 40 psi and even then it felt like it was floating on gravel. Now I run 33 upfront and 32 to 35 in the rear depending on if I’m towing. Being in the 60+ neighborhood on tires like that is wild, I’m sure it road like trash and you probably already have some bad wear patterns.
After I posted this, I lowered them to 40. It was like riding on butter. So nice and I had traction and yes, It road like trash times 1000. I figured that's what I got myself into having a lifted truck on 35's. Never knew... :)
 
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Dean2

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I run goofyear Duratrac 275 70 18 on my 2021 2500 with the 6.4. I run 45 front 40 rear most of the time. If I load it real heavy I go up yo 50 and 45. I used alphaobd to turn down the thresholds so I dont get the low pressure warnig. Way better ride and far better traction. Door sticker says 65 front 60 back.

Check out inflation chart. 45 a trie exceeds max GVW.

 
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larrymax

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Looks like I'm buying alphaobd. What is the best OBD adaptor for my truck? 2014 Ram 6.4 4x4?
 

KerryinTN

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I got an Autel MaxiCOM MK808BT for under $500 and it does have the tire pressure range warning change capability. It’s overkill for just that purpose, but I’ve also used it to diag the money light (emission issue) and program new smart keys.
 

lpennock

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Correct way is to use the TRA load table to set your pressures based on actual loading. A trip to the CAT scales at your local truck stop would give you the actual ratings but these numbers should be close.
35x12.50 r20 TRA per tire load@pressure
For 6200lb front axle weight
3195@65psi.
For 3500lb Unloaded rear axle weight
1895@30psi
For 4000lb Unloaded rear axle weight
2095@35psi
Max rated load assuming it is a E rated (Load Rating 121) tire is a rear loaded axle rating of 6390lb (3195lb*2)

As others have said you can use AlfaOBD to reprogram the thresholds.
 

Dusty

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Correct way is to use the TRA load table to set your pressures based on actual loading. A trip to the CAT scales at your local truck stop would give you the actual ratings but these numbers should be close.
35x12.50 r20 TRA per tire load@pressure
For 6200lb front axle weight
3195@65psi.
For 3500lb Unloaded rear axle weight
1895@30psi
For 4000lb Unloaded rear axle weight
2095@35psi
Max rated load assuming it is a E rated (Load Rating 121) tire is a rear loaded axle rating of 6390lb (3195lb*2)

As others have said you can use AlfaOBD to reprogram the thresholds.
Has anyone successfully changed the TPMS values on an older 2500-3500?

This was attempted on my son's 2014 2500 and couldn't be done.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 122426 miles.
 
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