I'm going to go against the grain here. There's no critical threshold for 42 PSI, and things won't magically explode at pressures below that.
Understand that the OEM inflation pressure is not likely composed of only load handling. Which makes the whole RCTIP methodology flawed. And even if it is, it is for the fully rated GVWR and highest speed rating for the vehicle. And it includes margin. Any LC is not likely being used in that way on a regular basis.
Also understand that the stock vehicle suspension assumes a certain tire sidewall spring rate. 42PSI on a heavier LT tire is going to cause the vehicle to be skittish at high speeds, especially bumpier surfaces, with the tire not staying on planted on the road. That is more of a concern than any supposed fear, uncertainty, and doubt about an assumed magical 42 PSI load carrying number.
If the ride feels too firm and brittle, it is. I'd encourage you to try 38PSI or lower. You can always re-inflate.
RCTIP on this forum is highly flawed and has propagated dangerously as a false requirement.
How did i not see this beautiful post.
Let me help you there Teckis, as i am fond of speaking my mind despite " social perceptions" boogey man which is laughable to me.
Youre the only one speaking the truth, and you're 100% accurate.
Ive read some of your old comments as well when you actually acknowledge sidewall rigidity as factor in performance and not just some arbitrary PSI.
Theres a lot that goes into this ideal pressure rec. and almost no one here is considering those things.
Practically everyone listening to the advice in this thread is running a suboptimal PSI. Specially if you rely on the resident "expert". Not to mention actual load inst even measured! LOOOOOOOL. Ive gone to great lengths determining my ideal needs and have written about it plenty in my own threads. It is nowhere near what the consensus would believe is "correct".
First of all throw the inflation chart out the window, it's being misused. Most of the information and practices it adheres to are severly outdated anyway.
Todays LT tires have amazing thermal management and will be completely safe down into the 20s even. You're also trashing your suspension at 40+ on most setups.
P tires as well are baby soft when you put 7,000 lbs on them and will not handle the way people think at "recommended" pressures when you start upsizing them. The entire road conformity profile changes. Don't be a victim of misinformation like i was. Do your own research and testing. And definitely dont blindly trust this forum. People here are punching above their weight class on A LOT of topics.
If anyone wants my advice, although you will have to take it with a huge grain of salt as this can actually impact your safety, listen up.
FOR LT TIRES ONLY:
Find out your average actual load (front and rear axle if you possibly can), not the max payload, not the curb weight, but average how you actually load the vehicle.
Find that value on the inflation table. That PSI is your goal AT OP TEMPERATURE. That includes high speed driving if you do that with it and does not include ever going far above that without conscious adjustment.
Theres really no minimum safe PSI when load is not considered, where your tire will heat and de bead will be dependent on many other factors. If your manufacturer lists a minimum PSI for your specific tire, follow it as best you can. Always experiment and watch the PSI, if you are filling up properly cold and the pressure fluctuates more than 15-20% when hot NOT CONSIDERING AMBIENT TEMP INCREASE, you are generating too much heat and should air up a bit until it achieves some level of homeostasis.
For P tires:
YOU CAN ALMOST NEVER SAFELY GO BELOW YOU DOOR JAMB RECOMMENDATION. Whatever that is, you are also probably going to be way above that if you plus size to retain safe maneuverability. There is not much additional comfort you can realistically achieve from going P-P. Pressure is not a dial that can be played with like that. There is a sweet spot for every setup and generally the more load is involved the smaller it becomes, specially when running P tires which dont provide any structural support in themselves. There is a reason why large sizes in P are hard to find. You will also be surprised how many manuf are using the same base carcass and just stamping s*** onto it. I don't recommend you go much larger than OEM fitment on any vehicle personally but there are cases where it is useful. Bottom line for Ps, get a slightly wider and taller tire and add pressure, don't reduce it unless you don't get on highways.
Please also note that towing will throw all of the above out the window. I highly recommend people weigh their loads when towing. I know some people dont even know to adjust for that on stock trucks.
I have by no means cracked the code to the point that i can give you an ultimate definitive piece of advice for any individual and I am still learning, but if i were you, I would start by understanding the measure of pounds per PSI or load per PSI. Graph it. There are a lot of interesting observations you can make when you consider that and remember that each tire has a different "load profile" for lack of better terms and then the tread etc will give you a diff handling profile on top of that (which everyone knows). Find yours if you have real OCD like i do and don't accept anything less than perfection anywhere you can exercise control.
Let the petty judgement begin!
