Ford F-150/F-250: How to Measure Trailer Tire Pressure

Your tires' PSI can vary depending on the weight you're carrying. Here is what you need to look for and how to check your PSI on your Ford F-150 or Super Duty's trailer.

By Tad Brunton - October 24, 2014
Contributors: MitchF150, Smokeywren

This article applies to the Ford F-150 (2004-2014) and the F-250, F-350 Super Duty (2005-2014).

The question of how much air we should fill our trailer's tires can be difficult to know for sure. However, the answer has always been in front of our eyes right on the tires themselves.

When you purchase tires for your trailer, you will find the manufacturer’s recommended PSI on the instruction sheet that comes with them. You can also call the tire manufacturer's 800 number and they will more than likely be able to assist you. The easiest way to determine proper PSI is to look on the sidewalls of your tires.

Those who do a great deal of towing take the PSI recommendations seriously. Theyknow that heat can destroy tires and that having too little air pressure can create much more heat than having higher air pressure can. If your tire tells you that the max cold PSI is 60, then they put 60 PSI in their tires. The tires will run cooler and last a lot longer when they run with the maximum recommended air pressure.

Once you determine the PSI required for your trailer tires, you need to pressurize each tire accordingly.

Tools Needed

  • Compressed air with hose and nozzle
  • Pressure guage

You can use your local gas station’s air facilities. Some are free and some cost up to $1 to use.

Step 1 – Put your truck in park

After it's in park, turn off your engine and activate the emergency brake. Always park your truck and trailer on level ground for safety.

Step 2 - Check the PSI in your tires

A simple tire gauge will tell you the actual PSI in your tires. If you don’t have one then you can use the air nozzle on the air pump at your gas station. When you put the end of the air nozzle over the tire stem and press and then release the handle, the air gauge will pop out and show you how much air is in the tire.

Step 3 - Fill your trailer tires

Connect the air nozzle to the tire stem and depress the handle. This will allow compressed air to enter the tire. Each time you release the handle the gauge will tell you how much air is in the tire. Stop filling at the max PSI.

Filling the trailer tires with the maximum pressure will not only keep the heat out and enable the tires to last longer, but you will notice a much more “solid” and smooth ride.

Remember to fill your tires equally and check them before each towing. Unevenly filled tires will cause uneven tire wear leading to shorter tire life, and could lead to other issues, such as trailer sway.

(Related Article: Why is My Trailer Swaying? - Ford-trucks.com)

Pro Tip

Most trailer tires will expire long before the tread has worn down because of the following:

  • The trailer sits more than it is towed
  • The sun deteriorates them faster because they are generally more cheaply made
  • Most TT and 5th wheel manufacturers put tires on their trailers that match the trailer weight (without consideration for extra weight)

A Note About Your Truck Tires' PSI When Pulling a Trailer

35 PSI is the norm for interstate cruising when in a truck with a tire size that begins with a "P" (for passenger). When loaded to the gills, pump the P-size truck tires up to the max on the sidewall, which is probably 44 PSI. For example, tire sizes P255/60R17, P265/60R18 and P275/55R20 should be pumped up to 44 PSI when towing heavy loads. But the rules change for the size LT245/70R17E tires that came with Ford's heavy-duty payload package. If your tires are LT245/70R17E, then pump them up to 65 PSI. Or if you are a stickler for details, then find the load/inflation table for your size tires and use that as a guide.

Below is a load inflation table for tire size LT245/70R17E:

PSIMax Load Per Tire
35 1690
40 1855
45 2010
50 2205
55 2315
60 2460
65 2600
70 2740
75 2875
80 3000

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