Tire pressures

So...OP was leaving this morning. Unless he left quite early, the answers he got here, would still leave him wondering. I will guess he left them at pressure tire shop used, when they installed. If he would have used the same rated tire, as per his trailer placard, 65 psi is indicated as needed inflation for his trailer.

What CapriRacer posted makes sense to many of us, but may have confused the OP even more??

At least he is leaving with new, quality tires. There is good info out there for him to research, concerning ST trailer tires. A former member here, Roger Marble has a dedicated RV tire blog that he could gain knowledge from.

Jerry

Word of caution: If you run too low of a pressure you run the risk of rolling the tire right off the rim when in a tight turn.
I agree OEMs were probably "D" rated and now you have "E" rated, thus the pressure difference.

The tires does NOT say to run 80psi!!!!!!! It says for MAX load air to 80psi. Unless you are overloading your axles 65psi will be JUST FINE!!!

Good call on the ENDURANCE!

Weight your rig and use the weight/inflation chart then add 5psi to that number. PER GY Tech Support when going up in load range.

50 PSI is max cold for a C rated ST tire
65 PSI is max cold for a D rated ST tire
80 PSI is max cold for a E rated ST tire

Your trailer probably originally had D rated tires hence the 65 PSI label. I always run my trailers tires at max cold.

The label on the 5th wheel also likely has a tire size and type on it also. If the tires you put on don’t match the label, then the pressure listed on the label is irrelevant. Your best bet is to go with the tire manufacturer’s tire load inflation chart.

Your tires do not say "run at 80 psi." They likely say that 80 psi is the maximum cold tire pressure. You can run them at any pressure you like up to 80 but don't exceed 80 cold.
Your trailer manufacturer must have known the weight of the trailer and how much pressure the tires would need to support that weight and thus they have the 65 psi sticker.
To know anything for sure you would need to weigh the trailer, look up the tire inflation tables, and see how much inflation pressure is necessary for that weight. I suspect if you do that it will be around 65 psi, not 80 psi.
You can run 80 if you want but it will result in a harsher, more bouncy ride for the trailer.

fj12ryder wrote:
Without knowing what your weight is, I would go for 80 psi. There are inflation pressure tables, and you can go from there, but 80 psi is a good place to start.

I agree, start at 80 psi. ST trailer tires are designed to run coolest, and perform best, at full sidewall pressure.

By your numbers, you have moved from an OEM D-rated tire, to a heavier, and higher rated E-rated tire. Endurance, likely does not offer a D-rated tire in your size.

I would not run the E tires at 65 psi. If they ride hard or cause unwanted bounce, I'd lower them to 75 psi, when cold.

It is alright to check tires when hot, as suggested above, but do not let air out to keep them at 80. The tires are designed for the increased pressure of heat, from rolling down the road, at towing speed.

Jerry

Pressure buildup Test:

Check tire pressures immediately before leaving. Ambient temperature, too, if you can.

Run at least an hour, then check again. You don't want more than 10% buildup excluding ambient temperature affects (2% for every 10F).

Without knowing what your weight is, I would go for 80 psi. There are inflation pressure tables, and you can go from there, but 80 psi is a good place to start.