Saturday, June 10, 2023


RV Tire Safety: RV weighing worksheet and selecting the PSI for your RV

What do we mean when we say “4-corner weights?

You have probably heard about the advisability of learning the actual load on each tire position on your RV. This is many times called “4-corner weight” in reference to the basic position of tires on vehicles, right and left, front and back. If you have a towable you may have one, two, or even three axles. So while the number 4 may not apply, the concept is the same. You should learn the load on tire(s) on each end of each axle.

If you attend a large RV convention such as FMCA events (check Conventions link) or Escapees SmartWeigh, there are some companies that offer the special service and use special portable scales that can give the load on individual tire positions.

Weigh To Go is another group.

Also, I understand that National Indoor RV Center (Dallas and Atlanta locations) offers scale weighing.

You might check with your local moving and storage companies, builder supply or even local sand and gravel suppliers.

Some of the above have extensive experience with RVs and can offer suggested levels of inflation needed. But others can simply tell you the scale reading. You do not need the accuracy of a “certified” scale, as offered by CAT at truck stops, as almost any heavy-duty “truck scale” is good enough for your needs.

But, you ask, how do I use the scale readings to learn the minimum inflation I need for my RV? That’s where this RVWorkSheet comes in. Simply download the PDF file and print it off. (You should also save a blank copy for future use or to share with other RV friends.)

The worksheet allows you to enter the various scale readings for your type of RV. With simple calculations, you learn the heavy end of each axle.

Using the Load & Inflation tables for your tires, as found HERE, you check for the MINIMUM inflation required to support the heaviest loaded tire for each axle. If you can’t find your exact brand or size tire in my list, you can use the information provided by Goodyear, Bridgestone, Michelin, or another tire company, as you will see that all the tables give very similar (+/- 5 PSI) numbers for identical size, type, and load range tires.

You can read a number of my posts on how to do the final calculations in THIS group of posts. Some even show examples of how to do the calculations and adjustments to get the final PSI, including a suggested “Reserve Load.”

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

Read more from Roger Marble on his blog at or on



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8 months ago

While you mentioned setting the inflation according tor the heaviest tire you also mentioned using a CAT Scale or a truck scale that only gives the total axle weight, or the average of both sides of the axle. That can under-inflate one side by 5 PSI to 10 PSI (on ours) due to the uneven weight distribution from side-to-side on an RV, unlike on a car or truck. What do you think about the advice to add 5% to the axle weight to get the heaviest tire inflation closer to its minimum pressure?

Example: an axle that has 6,000 lbs on one dual tire set and 6,500 lbs on the other dual tire set (almost an 8% difference) = 12,500 lbs or 6,250 per side. But adding 5% or 625 lbs to the axle weight takes it to 13,125 lbs total or 6,563 per tire. That puts it a lot closer to the actual “heaviest tire” true weight when using an axle weigh (6,500 actual versus 6,563 calculated versus 6,250). Does the side-to-side difference really matter or is it a distinction without a difference?

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