B arry's Tire Tech

This is a series of articles on the technical aspects of tires, their care and usage.

My primary purpose in these articles is to help people understand tires and thereby reduce the risks we all face every day.

..........and since tires is just about the only thing I know about..........

Please drop me a note if you have a topic you want to see:


Pressure Buildup Test:

Want to know if your tires are overloaded?

Below I present a test procedure to figure that out and a spreadsheet to help with the calculations.


Test Procedure:

  • Before starting out on an extended trip (at least an hour!), measure and record both the inflation pressures and the ambient temperature.
    • It's also a good idea to inspect the tires by rubbing a GLOVED hand over the entire tread surface. You are looking for bulges. If you find any, replace the tire immediately!

After an hour or so into the trip, stop and measure the inflation pressure and note how much pressure has built up.

You don't want more than a 10% buildup - excluding ambient temperature effects:

  • Ambient temperature effect = 2% per every 10ºF (5½ºC) change in ambient temperature.
  • If you get more than 10% pressure buildup (excluding temperature effects), you need more load carrying capacity in your tires - either more inflation pressure or a bigger tire size. Needless to say, you want to be aware of how heavily you are loading your vehicle. More Load = More Pressure build up!

Here's a spreadsheet to make the calculations easier:

Barry's Tire Tech: Pressure Buildup Calculator

  • This will open another tab with an uneditable copy.

  • Download the spreadsheet and open the download.

  • Click on "Enable Editing".

Be sure to change the units by clicking on the cell next to Choose Units . A Pulldown tab will appear.

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