RV Tire Safety: Is there an “optimal inflation” for RV tires … or not?

Is there an “optimal inflation” for RV tires? Many think the number in an RV sticker (aka tire placard)

or in tire Load & Inflation tables

is an “optimal” inflation or pressure. In fact, it is oftentimes just the MINIMUM pressure needed to support the GAWR (gross axle weight rating). However, that assumes a perfect 50/50 side-to-side split—which is unrealistic.

We tire engineers want to ALWAYS protect the tire from overload. We know that pressure will change with changes in the ambient temperature (air temperature in the shade). Also, we know that tires will ALWAYS get warmer when they are driven.

The pressures found in the Load & Inflation tables are almost universal across all tire companies. (A handful of Michelin sizes differ by 5 psi or so, so not significantly different.) They are not playing games with tire engineering science.

So, unless there is a specific reason (which should be mentioned in a post), we are ALWAYS talking about “cold” inflation pressure. We know that tire pressure changes by about 2% for each change in temperature of the tire, as I covered in these posts.

The short answer to all your tire inflation questions:

1. Get the weight on each RV axle from a truck scale (or similar).

2. If you do not get individual tire position weights (aka 4 corner weights), assume the heavy end of each axle is supporting 51 to 53% of the axle total.

3. Consult tire Load & inflation tables to learn the MINIMUM inflation to run based on the heavy end of each axle.

4. I suggest that your cold inflation on all tires on that axle, be at least 110% of the MINIMUM psi found in the table in #3 above, but do not exceed the max inflation rating for your wheel. (The number may be on the wheel or you may need to consult your RV company.)

5. I recommend that you ALWAYS run a TPMS with the low-pressure warning level set to the pressure in #3 above. This might take some calculation effort, as different TPMS have different ways of setting the warning level.

Have a tire question? Ask Roger on his new RV Tires Forum here. It’s hosted by RVtravel.com and moderated by Roger. He’ll be happy to help you.

Read more from Roger Marble on his blog at RVtiresafety.net or on RVtravel.com.

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