Truckers weigh their vehicles regularly so best bet is to find a truck scale someplace. At almost any truck stop you will be find a drive-on scale. Most of these are CAT scales or a Certified Automotive Truck scale. For a listing of scale locations throughout the US double click CAT Scale Locations to find one near you. In addition to truck stop scales some local gravel and concrete products companies or truck terminals have a public scale. Other places to get weighed are the FMCA or Good Sam rallies where RV Safety Education Foundation comes in or at Escapee Escapades where they also have scales for wheel weights. Some states leave the scales at truck weigh stations on when they are closed. Washington and Oregon welcome RVers to come in and use the scales when they are closed.
You need to know the weight of each axle and the total RV weight. Each axle is designed to carry a maximum weight and each tire also has a weight rating. As the weight increases, so must inflation pressure, up to the rated maximum. The wise RV owner uses the tire manufacturer’s inflation tables and knowledge of the wheel weights to determine the proper inflation for each tire for best ride, handling, and tire wear. It is also important to know how weight is distributed to gain proper balance of the load from side to side for best handling and comfort.
Rather than using just the weight of each axle and assuming that each tire is equally loaded, you should try to get a weight for each side at least once each year. To do this from a public scale you will need to locate one that does not have barricades along the sides to allow you to weigh once with all wheels on the pads and then a second time with only the wheels of one side on the pads so that you can subtract the weights of the single side from the totals to determine each wheel weight. Once you do that you can move things about in your storage to balance the load from side to side as much as possible. A difference of a few hundred pounds will not be problematic, but once you get much more than that it can affect handling of the RV. Many manufacturers do not put enough effort into proper weight balance of the RV when locating things like the water & waste tanks, the refrigerator, water heater and slides. You should try to have each side as nearly equal as possible. Once you know this, adjust tire inflation to the needs of the most heavily loaded tire on each wheel. Never run different air pressures in tires on the same axle. It is normal to have different inflation pressures in the front as compared to the rear on any vehicle if the weight tables suggest that.
For an example of weighing your RV, let's look at the following scenario. Remember that these are example weights only so you will have to substitute your numbers when checking your RV.
Assume that the RV to be weighed has a GVWR of 29,000#, a front axle weight rating of 12,000# and a rear axle rating of 20,000#. Individual wheel weighing scales give the following weight information.
With most truck scales you will get a ticket that lists each axle weight and a total weight for the vehicle. If this is the case then you would have received a total weight of 28,070# and axle weights of front 10,820# with rear of 17,250#, all well under the maximum ratings. Weighing the left side separately we would find 5,200# front and 8,870# on the rear.
On the two sides you will see that there is not a great difference in totals, but you might be able to improve on the 400#+ difference between the sides on each axle by moving heavy items in storage. If you are able to get the difference between the two sides to numbers no larger than this example it is probably not worth a great deal of effort to shift things around, but consider each axle individually and match the sides as much as possible.
Once things are as well balanced as possible and you are under the design limits for your RV, then next thing is to determine the proper inflation pressure for the tires of each axle.
Sample Chart of Tire Load Ratings |
||||||||
PSI |
|
80 |
85 |
90 |
95 |
100 |
105 |
110 |
Lbs per |
Singles |
4000 |
4235 |
4465 |
4710 |
5060 |
5405 |
5880 |
Duals |
7390 |
7820 |
8270 |
8710 |
9150 |
9620 |
10040 |
Checking the above load inflation table we find that the left-front corner weighs 5,200# which calls for a minimum air pressure of between 100 and 105 PSI. The
On the rear axle we have duals so well be using the lower row of numbers from the above chart. At 8,380 lbs our right-rear corner requires 95 PSI when you divide the weight by two for the dual tires. The left-rear weighs 8,870 so requires 100 PSI so all four tires on the rear axle should be inflated to 100#.
Looking to the front axle, the left would require 105# or the nearest choice that is above the weight found while the right wheel comes to 110# of inflation, also rounded up. Therefore you should inflate the tires on the front axle to 110# for safe and comfortable operation.
Many RV owners inflate their tires to whatever the pressure is that is on the tire sidewall, but that is the maximum air pressure which that tire is designed to run with and should only be used if you do not know the actual weight that is on that tire when traveling.
Proper loading of an RV is important for both tire wear and proper handling of the RV, whether a travel trailer, fifth wheel or on a motorhome. It is good practice to check weights annually and to check tire inflation each morning before travel.