What Pressure Should Trailer Tire Rated at 80 PSI Max be Inflated to

Updated 04/07/2025 | Published 04/29/2017

Question:

I have a single axle boat trailer with 5.30 X 12 bias tires. The only psi stated on the tire is Maxium load psi is 80 psi Cold. What tire pressure should I maintain them? Thanks

asked by: Denny R

Helpful Expert Reply:

Trailer tires should be inflated when they are cold and should be inflated to the max psi rating on the sidewall. In your case you would want to run 80 psi.

If you don't inflate them to the max psi figure you will lose weight capacity and potentially cause the tires to overheat and fail.

expert reply by: Jameson C

Pj A.

1/10/2021

OK...so I see you are recommending the max pressure COLD. What if I live in Flagstaff AZ...7000 feet elevation in winter and it is 32 degrees when I measure the PSI. What does your COLD mean? 60 degrees is cold in Phoenix AZ...

Jon G.

1/14/2021

The cold psi means the psi rating after the trailer has been sitting overnight. When you start heading down the highway the tires will naturally heat up so when we are saying cold we mean when the trailer hasn't been towed around for a while.

Pj A.

1/21/2021

@JonG Thanks for your response Jon. I'm not sure I phrased my question clearly. When I measure the PSI of my tires before heading down the highway and the air temp is 32 degrees, I'm going to get a different reading than if I measure the PSI of my tires before heading down the highway and the air temp is 60 degrees. The reason I am asking is that if I fill my trailer tires to 80 PSI in Flagstaff with the air temp at 32 degrees and head down the highway to Phoenix where the air temp is MUCH higher (70-80 degrees by the time I arrive) will the pressure in my tires be too high?

Jon G.

1/21/2021

@PJA Ah, I see now. In that case, yes, it would be possible that your pressure would be too high. If you're going to be traveling to climates that change that drastically in 1 trip then you might consider getting a TPMS (tire pressure monitor system) to install on your trailer. This will allow you to actively monitor your tire pressure and have alerts set to go off if your pressure or temperature get too high. Attached is a link to our selection for you to filter through.

Helpful Links

dept-pg-tpms_sensor.aspx

See All (8) Replies to Pj A. ∨

Dan R.

4/7/2025

I have had 4 or 5 tires (8x4.5 bias play) tires all "bulge" shortly after being inflated to max pressure (either 90 or 60 psi) and driven one to two hundred miles. I have had several friends experience the same. By bulge i mean about a baseball sized bulge, still holding air, but obviously ruining the tire. I finally decided to never inflate to the max and always run a little under- 75 on the 90 psi and 50 on the 60 psi. I have not had this bulge failure since. Also, I am no where near max load capacity on my tires, usually around 50-70%. Thoughts?

Jameson C.

4/7/2025

@DanR How fast are you travelling with those tires? If you are exceeding the speed rating that is on the tire sidewall that will cause it to overheat and fail. A lot of tires in that size range are only rated for 65 MPH.