The importance of knowing your RV’s ‘4-corner weights’

If you have been paying attention to information on tires in RV application, you probably have heard the phrase “4-corner weights.” Let’s dig into the basic concept of vehicle weight and why this is so important.

Most cars, trucks and RVs have four tire positions. Yes, I know that some of you have small “pop-up” trailers with a single axle and only two tires. But I do not recall hearing about a small trailer having hundreds more pounds load on the tire on the “driver side” versus the tire on the “passenger side” of the RV, for example. I have, however, heard of some large RVs having more than 1,000 lbs. more load on one end of an axle than the load on the other end, and that is what concerns me.

RV tire loading

For the purpose of RV tire loading, we are focusing on the four positions of right front, left front, right rear and left rear. Most big and heavy RVs have “dual” tires on the rear axle, so we are talking about the tire position, not the individual tires. Yes, some very large Class A RVs also have an extra axle or “tag” in the rear. When the topic is “4-corner weights,” we are not talking about the load on an axle but the tire positions.

I am concerned with “4-corner weight” because a vehicle may have a significant unbalance end-to-end on an axle. The owner gets an axle weight and may simply assume a 50/50 end-to-end load split. In that case, we are looking at the potential of serious tire overload. Hopefully, most of you realize that tire overload is the reason for many tire failures.

Here are links on how some get their weights. To weigh your RV (motorhome or travel trailer) on a CAT Scale, you need to drive onto the scale with the RV positioned correctly and use the CAT Scale app or speak with a scale operator. CAT Scales are commonly found at truck stops and are designed for weighing commercial vehicles, but they also accommodate RVs.

• Read about steps for weighing your RV on a CAT Scale here.
• Find a CAT Scale near you through the CAT Scale Locator app or website.

NOTE: Most CAT Scales have a guard rail that prevents you from being off-center side-to-side.

RVs may not be loaded evenly

I fully realize that learning the “4-corner weights” is not always easy, as very few truck weight platforms do individual tire positions. Commercial trucks have “axle weight” laws and regulations. However, the reality is that most trucks have their load more evenly distributed, side to side.

We RV owners have some of our “heavy stuff” built into the RV. So, a heavy commercial refrigerator, the water holding tank, and a slide-out could all be on the driver’s side of the vehicle. However, relatively lightweight items like clothes or toilets could be on the passenger side. If the owner gets an axle weight and simply assumes a 50/50 end-to-end load split, we are looking at the potential of serious tire overload.

Getting your RV “4-corner weighed”

If you attend RV gatherings such as an FRVA convention or an Escapees event, there are many times people there who do RV-focused “4-corner weighing.”

Here is information from Recreation Vehicle Safety Education Foundation (RVSEF) on Wheel Position Weighing.

Here is information from Escapees RV Club on SmartWeigh.

Yes, it will take a little effort to get real “4-corner weights.”

HERE is a post from my blog on this topic.

This is my RV on a scale in Oregon. The red circle is the weight sign.

This “state scale” is turned on even with the scale officially closed. I took the opportunity a few years ago to get my own “4-corner weights” and it was free.

What to do until you get your RV “4-corner weighed”

Some have asked what to do until they get actual individual tire position weights. I have offered that they at least get CAT Scale axle weight and assume one axle end is supporting 52% to 54% of the load. But this is a poor substitute for learning the facts.

Finally: Remember that once you learn YOUR actual axle end weight you need to use the “heavy-end-weight” for each axle and consult the Load Inflation tables to learn the MINIMUM inflation required to support your load.

Roger Marble

MORE POSTS FROM ROGER ON 4-CORNER WEIGHTS

• 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?

*****

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.

Please enable JavaScript in your browser to complete this form.

Name *

First

Last

Email *

Question or message *

Photo upload

Drag & Drop Files, Choose Files to Upload

Submit

RVT1214