Tire Pressure Calculation

[MEGARMS]

2023 Ram 1500 Laramie
2" BDS LIft Kit (Fox 2.0 Coilover)
Toyo Open Country AT III (LT285 55R 22) (OEM tires were 285 45R 22)

New lift kit and tires. The ride is far from what I was expecting (not as smooth as I would like). The Max PSI on the sidewall is 80 lbs, however we started with 50 lbs. I called Toyo and they calculated that I need 46 lbs, however it is still rougher than I would like. I then found this Tire Pressure Calculator which recommended 38lbs. It claims the difference to be due to a 10% overage in load capacity on passenger tires that are used on Light Trucks, Vans, and SUVs.

Tire Pressure Calculator

Can anybody offer any insight? I hesitate to go against the manufacturer's suggestions, but I am not happy with this ride.

 

[2021EcoDiesel]

What does your door jamb sticker say? I would run them at that pressure and see how happy you are. If your tires are E Rated they will never be as soft as the factory ride, but they shouldn't ride like they are made of limestone either. For the record I run my tires at 34 psi cold, the sticker says 32 psi cold for the factory P275/55R20's. Current tires are LT285/65R20 10 plies and I'm happy with the ride at 34 psi. 53,000 miles on the them and they still have 70% tread left and have had no blowouts or issues.

 

[MEGARMS]

What does your door jamb sticker say? I would run them at that pressure and see how happy you are. If your tires are E Rated they will never be as soft as the factory ride, but they shouldn't ride like they are made of limestone either. For the record I run my tires at 34 psi cold, the sticker says 32 psi cold for the factory P275/55R20's. Current tires are LT285/65R20 10 plies and I'm happy with the ride at 34 psi. 53,000 miles on the them and they still have 70% tread left and have had no blowouts or issues.

That is interesting. I really know nothing about this and just don’t want to screw anything up causing an unsafe condition or limiting the life of the tires.

Are there any risks associated with experimenting all the way down to 36 lbs like the door jam says?

 

[Scram1500]

I monitored my tread wear before landing on the correct psi for 33 inch tires E rated tires, 42 front, 32 rear. There is also the chalk test

How To Find The Right Tire Pressure For Your 4x4 Using Chalk - The Dirt by 4WP

Improve Fuel Economy, Tire Life, Traction And Vehicle Ride With Proper Tire Pressure

www.4wheelparts.com

 

[Josh24]

Definitely experiment with lower pressures. I'm running the same tires in the same size on my limited at around 38 and it rides good. Stiffer than the stock p285/45/22 but really nice for a 10 ply rated tire.

 

[tommycc]

Call the tire manufacture. tell them what you have, and they will tell you what pressure to run. Once you change tire size and load rating the door jam sticker no longer applies

 

[2021EcoDiesel]

What these guys are saying^. Chalk test can help you dial it in but yeah go ahead and drop them to 36 if you'd like. You may notice more sidewall deflection when rolling over a curb or something like that, but the tires should hold up just fine even as low as 32 for normal driving. If you were hauling or towing everyday I'd say pump em up to 40 or so, but for normal DD'ing you are fine in the 30's.

Edited: Realized you had already spoken to Toyo. was going to suggest reaching out to them.

 

[tommycc]

sounds like he has E rated tires . so tires pressure is way different

 

[2021EcoDiesel]

sounds like he has E rated tires . so tires pressure is way different

Yes they are E Rated. So are mine.

 

[MEGARMS]

sounds like he has E rated tires . so tires pressure is way different

I already called Toyo. They said 46 lbs. Still is not too comfy.

 

[MEGARMS]

Definitely experiment with lower pressures. I'm running the same tires in the same size on my limited at around 38 and it rides good. Stiffer than the stock p285/45/22 but really nice for a 10 ply rated tire.

Excellent. I was hoping someone with the same tires would chime in. I'm going to drop them to 38 and see how it rides and then do the chalk test once it dries up outside.

 

[CHeYeNNe71]

I forget what I ran 37's at, but think around 35ish. Just mess with the pressures until you're happy, but the trade off might be tire wear. Just keep an eye on the wear. Also as mentioned the Chalk Test.

 

[jadatis]

2023 Ram 1500 Laramie
2" BDS LIft Kit (Fox 2.0 Coilover)
Toyo Open Country AT III (LT285 55R 22) (OEM tires were 285 45R 22)

New lift kit and tires. The ride is far from what I was expecting (not as smooth as I would like). The Max PSI on the sidewall is 80 lbs, however we started with 50 lbs. I called Toyo and they calculated that I need 46 lbs, however it is still rougher than I would like. I then found this Tire Pressure Calculator which recommended 38lbs. It claims the difference to be due to a 10% overage in load capacity on passenger tires that are used on Light Trucks, Vans, and SUVs.

Tire Pressure Calculator

Can anybody offer any insight? I hesitate to go against the manufacturer's suggestions, but I am not happy with this ride.

This " pigheaded Dutch selfdeclared tyrepressure specialist" registered to give answer here.
The LT (at 80 psi) needs higher pressure for same load then the P-tire(at 35 or 42psi) to get same deflection, so heatproduction.
But the hight/width division ( Aspect Ratio AR) is 55 instead of 45, so this compensates that. So I estimate, you can use same pressure.

Can make a axleload/ cold pressure list for both tires, if you give me next, read from sidewall.

1. Maximum load or loadindex
2. Kind of tire to determine the reference-pressure ( your LT E-load AT 80 psi, OEM SL AT 36 psi XL AT 42 psi)
3 Speedcode, less important.

Then I will make list with maximum reserve, at wich comfort and gripp is still acceptable. Then you can do 2 things.
Best is to determine axleloads in your use 99% acurate, and search back in list.
Succes with that, the most tricky part, and your responcibility.
Second is find GAWR 's and search them back in the list, or search recomended pressure in OEM list for the axleloadcapacity it represents, and search that back in the LT list for new cold pressure.

Also give how you want the lists, in psi or bar, lbs or kg.

 

[MEGARMS]

Can make a axleload/ cold pressure list for both tires, if you give me next, read from sidewall.

1. Maximum load or loadindex
2. Kind of tire to determine the reference-pressure ( your LT E-load AT 80 psi, OEM SL AT 36 psi XL AT 42 psi)
3 Speedcode, less important.

Then I will make list with maximum reserve, at wich comfort and gripp is still acceptable. Then you can do 2 things.
Best is to determine axleloads in your use 99% acurate, and search back in list.
Succes with that, the most tricky part, and your responcibility.
Second is find GAWR 's and search them back in the list, or search recomended pressure in OEM list for the axleloadcapacity it represents, and search that back in the LT list for new cold pressure.

Also give how you want the lists, in psi or bar, lbs or kg.

Sorry, but I am a but as a self-declared tire pressure idiot, I have to say that I am confused by what you are asking for.

 

[HSKR R/T]

FWIW, I am running my 35x12.50 Radar Renegade AT-Pro at 30psi rear and 35psi front. They have a load range of E.

 

[Bt10]

Sorry, but I am a but as a self-declared tire pressure idiot, I have to say that I am confused by what you are asking for.

He's asking for your info so he can manually calculate your new tire pressure, and give you the same answer as the online Calculator.

Personally, I'm going a little lower on the rears, since I don't have the box loaded.

 

[Scram1500]

The online calculator is assuming you're at full payload, not empty

 

[kjaminet22]

I'm running the same size Toyo's with 2" level and set them at 38. I was pleasantly surprised how close the ride is to stock.

 

[Ready Go]

I "F" around with tire pressures on all my vehicles (I LOVE dialing in suspensions! and have had 80+ vehicles in my life so far!)

I find that almost every time, no matter what tires/sizes/camber/caster/etc I end up with, the OEM recommended Tire PSI is what works the best!

Having said that, my current Ram suspension setup is still using the OEM 20x9" with 275/55-20 Bridgestone Deuler H/Ls and the OEM Tire Pressure recommended is 39psi cold, but I've found that 37-38psi cold gives the best/smoothest ride and the electronic steering rack actually feels more "manual" and less "light"...similar to how an "old school" 12:1 AGR steering box was tighter/stiffer than an OEM 17:1 variable rate steering box back in the day.

I wouldn't be afraid to try a "low" Tire PSI in search of better comfort, etc. May or may not work, but give it a try. Chalk test is useful too, but I mostly go with the "butt gauge" and "steering feel" as my tester.

 

[Sigfla]

Same setup. Started at 36 ride was close to stock. Drove over a curb and got concerned with wheel deflection. Also went down the rabbit hole of pressure comparators on the web. Went up to 40 and ride got stiffer. Was about to drop to 38 as I feel that’s the magic number but 36 should be perfectly fine according to my tire guys. You’re pushing a heavier taller tire so that snappy front end is gonna slow down a bit.