Tire Pressure

3th possibility is to let me calculate it for you with my Motorhome-tire-pressure-calculator.

For that I need from vehicle.
Seperate weighed wheel loads in the condition you load it, but Axle weighing can do.
If you dont have one of those , we will have to do with the GAWR's( gross axle weight ratings), asuming that you are not allowed to go over them, but for rear it happens, and I take a large reserve to cover that.
Then also give GVWR ( gross vehicle weight rating)to make it complete.

From tires.
Maximum load or loadindex ( when different kind specifie)
Loadkind so for instance C-load/6PR or E-load/10PR or mayby yust P-tires or XL/reinforced/Extraload, to detemine the pressure needed for the maximum load, also called maxloadpressure or reference-pressure, wich is not the maximum cold pressure of the tire.
Then also give sises and speedcode of tires ( letter between J and Q or S,T,H,V,W,Y)
And camber angle of rear tires mostly.
Also yudge if the tires are for off-road use or have the looks of that, with large profile blocks covering part of the sidewall.

Then I can calculate the lowest save pressure and first add a reserve to the loads that gives savety margin but still comfort and gripp is acceptable.

About the TPMS , it can be reset to an other pressure , sometimes even the reserves can be set too. Every system though different manual , so you have to search for that.

I use the load index tables from the manufactures web sites. 65 front 24/7 rears 45 empty, 65 loaded with 5er. These are E rated tires that state 80 MAX. I'm just not at MAX weight to warrant 80 lbs.
This is like the gas vs diesel question, always two opinions.

For my 2500 Dodge/Cummins with LT265/70-17 E I've found 65 psi in the front works the best. My trucks front axles don't carry any pin weight so I leave them at 65 psi 24/7.

I've found 45 psi when running empty and 70 psi with 2200 lbs of pin weight for my 5er or 80 psi with the 16k GN trailers.

This truck has 225k miles and is on its third set of tires.

The most accurate method is to weigh your TV with your rig hitched up and determine how much weight your rear tires are supporting. Go to tire manufacturer's website to view recommended pressures for the weight your specific tire is carrying.

My E-rated tires can easily support the weight of our rig so I inflate mine to a bit over 70 psi as max 80 psi provides too harsh of a ride, front tires are set to 60-65 psi. The ST tires on our rig are set to max pressure as stated on sidewall as ST tires perform better at max pressure.

It's not a simpler "yes/no" type of question. The DOT safety plate is required by law to list the correct inflation to enable carrying the GVWR of your vehicle PROVIDED you have the OEM tires on it or equal replacement tires. If you change tire size or type the plate will probably no longer be correct. In that case you are kind of on your own but there is help. Many tire manufacturers provide an inflation table which is based on the total amount of weight the tires are carrying. This could be used to get your answer when it's available.

It is ALWAYS SAFE to inflate tires to their maximum sidewall rating (set pressure when tires are cold) but this does NOT insure that you will get the maximum performance or tire wear from them. To come up with the correct answer it requires some research on your part but the information IS out there.

For what it's worth, your TPMS should be able to be SET for the inflation pressure you decide to run (at least that's the case on Fords)but it's often NOT an easy adjustment. Your dealer can do it for you based on what you want.
good luck / Skip

We always start with the assumption you have a vehicle rated for the tires. Because if you use tires for a heavy load beyond the vehicle original design, and current condition you will still have a bad tow, even if the tires are inflated to Max for their design max load. So if you have a vehicle in condition that is the same as the new design specifications then use the design specification rated tires or better rating, never less than original design. So the weight being at max for vehicle may be the same as the vehicle or better. That higher rated tire can't be loaded beyond the vehicle design load. So if you are at max vehicle load, then depending on the tire inflate to make the tire tread surface pushing on the pavement all the way across the tread evenly. That is done in a static,(non moving and level),measurement with trailer and tow vehicle no more than 4 inches up or down from level to each other. The trailer should have 60% of the load in front of the trailer axle or center of axles, so tongue weight is enough to keep the trailer from wagging the rear of itself. Assuming that has been done, then the tongue weight should be checked to see if it exceeds the manufactures design and current condition of the hitch and towing weight of the tow vehicle. That is done by jacking the trailer off the hitch of the tow vehicle until the load is off the tow vehicle, always keeping safety in mind, blocking the wheels so nothing moves. Always then return the trailer to the seated position of the hitch and lock them together. That being done and within specifications then finally the tires can be inflated to the loads you have determined, never more than max design of the tire and possibly slightly less as the weight is in proportion to the design of the tow vehicle, which can be less than the design of the tires if you used over rated tires beyond the tow vehicles specification. You want stability, not hard ride at rear of the tow vehicle, as then the weight will be transferred to the front end of the tow vehicle making steering plow due to turning wheels up front having pressure on sidewalls greater than the rear tires that for the most part going straight. Top heavy loaded trailers will also cause instability as loads shift as pavement slope changes side to side. Always inflate the tires of the trailer to the maximum weighted side, as determined by a scale designed for side readings. That eliminates the shifting weight factor in dynamic,( moving) conditions. An experienced tower knows the correct feel for the proper inflation and many times can tell by looking at the tires and how they come down to the pavement on the sides. Others know from wear if the tires are being over inflated, as they wear on the center, and under inflated wear on the outsides. Remember max inflation at cold tire is set so that when it's hot it has enough air to keep it touching the pavement. Hot tires read higher pressure so always check when cold, or use the manufactures calculators which require temperature readings at the surface of the tire to convert what you need. This is Physics and if you ever paid attention to a NASCAR race you always hear the drivers saying how the vehicle is handling the track, and do pit stops for suspension and inflation adjustments to get maximum handling so they can win.

Google your tire brand name and load rating ie: (goodyear load rating), and the manufacturer's PSI recommendation for your tire and load will be listed.

coolbreeze01 wrote:
80lbs in the rear and 65lbs in the front has worked just fine in my diesel pickups with E rated tires, over the last 20 years or so. Have fun.

I adjust the rear pressure based on the load, running 80 psi leads to harsher ride, very easy wheel spin on wet pavement. I run about 50 psi empty, and 70 to 75 loaded Rear is about 5,500# with the fiver hooked up.

Most tire manufacturers have websites with a chart for each tire model that shows the recommended pressure for the load.

The rule of thumb is to use the pressure shown on the sidewall of each tire. The plate on the door only applies to the standard tires put on vehicles when built. The plate is not updated if an optional tire setup is ordered or aftermarket tires are added. For example a Chevy 2500 truck at work shows 32 PSI on the door panel. The sidewall of the load range E tires on the truck show 80 PSI if we ran them at 32PSI the tires would fail due to heat.

Use the pressure on the manufacturers chart or the sidewall. I always keep my tires on every vehicle at the maximum pressure shown on the sidewall. It doesn't matter if the vehicle is carrying a load or not I still use the max sidewall pressure. I don't have to spend time adjusting the pressure when loaded or not loaded.

80lbs in the rear and 65lbs in the front has worked just fine in my diesel pickups with E rated tires, over the last 20 years or so. Have fun.