RV Tire Safety: Readers’ questions about setting pressure and best gauge

I received this question from a Class A owner about how and when to set their tire pressure depending on fluctuating ambient temperature:

We have a Class A diesel motorhome. Our maximum cold pressure on the front tires is 120 psi. After weighing our coach we need to run 113 psi. We add an extra 5 psi for safety, so our cold pressure is 118 psi.

We live along the Texas coast, so our summer morning temps can be in the high 70s or low 80s. Before leaving for a trip, I set my cold pressure to 118 psi first thing in the morning.

During the summer we often travel to Colorado or the mountains of New Mexico, chasing the cooler temperatures. A few weeks ago while in New Mexico, the morning temperature was in the high 40s and my tire pressure had dropped to 106. We were leaving that morning for Amarillo, TX. The high that day in Amarillo was to be 101. My dilemma: Add air to increase my pressure to 118 and chance once getting to Amarillo of having my pressures into the high 130s or low 140s; or drive several miles on the lower pressure tires knowing that they would increase in pressure in several miles to a safe traveling pressure.

What I did was to add about 5 psi to each of my front tires. Upon reaching Amarillo, my pressures were in the mid- to high-130s. The next morning before starting our day, I checked the pressures and released about 5 psi in each front tire to get me to my normal pressures of 118 psi.

My answer:

Yes, you set the COLD Inflation Pressure in the morning before you start to travel and before the tires have warmed up from travel or being in the direct sun. You do not have to worry about the increase as you travel into warmer parts of the country or as the tire warms up from travel.

You should never travel on underinflated or low-pressure tires. Your 130 or 140 psi is not a problem.

You can adjust to the cooler temperature and lower psi the next morning after the tires have cooled down.

Your +5 psi is a good idea. That is about what I use on my RV.

Side question: Where did you get the suggestion to inflate to 113 psi cold? The Load Inflation tables are usually arranged in increments of 5 or 10 psi. You should not interpret the inflation between the individual boxes found in the tables. If you need more, then jump up to the next level.

It also sounds like you are misinterpreting the “Max Psi” info on the sidewall of your tire. Here is a post with more info on that topic.

My recommendation for a tire pressure gauge

I got this request:

How about a recommendation for a quality tire pressure gauge? I no longer trust the typical stick gauge.

I have found the Accutire MS-4021 Digital Tire Pressure Gauge to be very accurate. I have three and they always read +/- 0.5 psi from the ISO Laboratory Master I used to check my gauges.

Roger Marble

*****

If you have tire questions, check out Roger’s Blog as well as his posts on RVtravel.com. There are hundreds of posts covering everything to do with tires.

If you still have a question for Roger after searching the above posts, send your inquiries to him using the form below.

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