Assuming you confirm your RV load every year or so, I suggest you do the following.
While getting scale readings, with the RV loaded to the heaviest you expect to be (and hooked up if it is a towable), get each axle of the RV weighed individually. This will help you when confirming the MINIMUM cold inflation required for the tires.
Learn the heaviest axle weight for each axle. If you have two or more axles on a “towable” RV trailer, be sure to weigh each axle by itself and use the heaviest loaded axle as the reference. If you have a motorhome, you need to get each axle weight by itself. This might require a couple of readings.
If you have tandem or even triple axles, as seen on some large 5th wheel trailers, add 10% to the heaviest axle weight. Since there is a 0% chance that both ends of an axle are supporting exactly 50% of the total on that axle, we need to build in some “fudge factor” to compensate for the variation.
If you are able to get individual tire position weights, i.e., “4-corner weights,” you do not need to add this 10% “fudge factor”.
Use the heaviest weight number when consulting the Load & Inflation tables to learn the MINIMUM Cold Inflation you should use. Some people like to add 5 PSI to avoid having to add air when the weather changes.
Set the Low Pressure warning level on your tire pressure monitoring system (TPMS) to the table MINIMUM Cold Inflation.
Test the TPMS
Once a year, test each sensor by partially unscrewing to confirm the warning level the driver can hear from the TPMS.
Be sure to reinflate the tires after running the test!
We are trying to ensure we are providing enough pressure to support the heaviest loaded tires. It is recommended that you add some margin in PSI so you do not need to check your inflation every day.
On my Class C, I got a “4-corner” weight from RVSAFETY.com (RV Safety & Education Foundation) while at an RV convention. Using the heaviest loaded tire on each axle, I consulted the Load & Inflation tables for my size tires. I used that number as my “Low Pressure Warning Level” on my TPMS. I then added 5 PSI to the table number to learn my “Morning Cold Inflation PSI”.
My driving (warm tire) PSI runs about +8 to +12 PSI above my “Morning Cold Inflation PSI,” which is just fine. Following this has meant that I only need to “top off” my tire pressure each spring before I start traveling.
It is just that easy and has worked for me since 2007. I think this should also work for you unless you are traveling between Phoenix in August and Alaska in November, when you change your “Morning Cold Inflation PSI” twice a year.
Roger Marble
RELATED
- The importance of knowing your RV’s ‘4-corner weights’
- If I upsize my RV’s tires, can I lower their inflation?
- A relevant question (plus much info) on 4-corner weights
- What does RV “weight creep” have to do with tire safety?
- Weighing an RV – 4-corner or CAT scale?
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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.
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RVT1216
Thank you for the reminder to know the axle weights (if not tire-position weights) and properly inflate the associated tires, Roger! Have a great week and safe travels!