The numbers that matter are all on the rig, and almost none of them are in the brochure. The brochure prints a dry weight for a base unit that isn't yours, a tow rating for a trim you may not have, and a generator's peak watts in the largest type on the box. The labels print the figures for the unit in front of you. Below, plate by plate: where it is, what each line means, the line to enter in bold, and the lines to walk past. A trailer or motorhome can carry three weight labels: a yellow cargo label and a certification label, both federal, and often a weight sticker of the maker's own. Every section ends with a link to the field it fills in My Rig, so you can do this once with a flashlight and never again.
The yellow cargo label
Where: Inside the entry door. For motorhomes and RV trailers up to 10,000 lb GVWR, the federal rule puts it on the inside of the forward-most door on the passenger (right) side, black print on yellow, with the VIN on it; if it’s gone, the maker can reprint it from the VIN. Heavier rigs fall outside the rule; look for the maker’s own label in the same place. (49 CFR 571.110, S9.3)
- VIN
- 1XYZ…ignore · ties the label to this unit
- "THE WEIGHT OF CARGO SHOULD NEVER EXCEED"
- 2,065 lb← enter this · CCC: GVWR minus the weight as built, full propane included. A motorhome’s label reads "occupants and cargo" (OCCC) and adds the belted seating count, because the people count too, and so does the tongue weight of anything it tows
- "CAUTION: A full load of water equals"
- 432 lb of cargo @ 8.3 lb/gal← enter this · water rides as cargo and comes out of the line above; divide by 8.3 for the fresh tank’s gallons
Ignore: Any idea that it covers what the dealer added. It describes the RV as configured for delivery to the dealer; weight added before the sale beyond 100 lb (or 1.5% of GVWR, if that is less) calls for a correction label beside it, and whatever goes on after you buy it (batteries, a hitch, solar) comes out of the cargo line on your own math.
The certification label and tire placard
Where: On a trailer, the federal certification label is on the forward half of the left side, readable from outside, and the tire placard sits next to it. On a motorhome both go by the driver’s seat, on the door jamb, the same as on a truck. (49 CFR 567.4; 571.110, S4.3)
- GVWR
- 8,495 lb← enter this · the loaded limit, and the number the towing and cargo checks use
- GAWR (each axle)
- 4,400 lb × 2← enter this · per axle; the CAT scale check sums them
- Tire size / cold psi
- ST225/75R15 · 80 psi← enter this · from the tire placard: the pressure the axle rating assumes
Ignore: Adding up the GAWRs to get a weight limit. On a trailer the axles and the tongue together have to carry the GVWR (S9.2), so the axles alone can rate more or less than it; the GVWR is the limit.
The maker’s weight sticker
Where: Wherever the maker puts it: near the yellow label, on the sidewall, or only in the paperwork. It is not one of the federal labels. Makers add it for the unloaded vehicle weight and the hitch or pin weight as the RV left the factory.
- UVW / dry weight
- 6,430 lb← enter this · as built, with factory options and full propane. If your rig has only the yellow label, GVWR minus the cargo line gives it
- Hitch weight (dry)
- 720 lb← enter this · a floor for your tongue weight, which rises as you load; measure it loaded
Ignore: The brochure’s "dry weight" and "hitch weight": they’re for a base unit without the options on yours. Any number with "up to" in front of it.
The truck’s door-jamb stickers
Where: Open the driver’s door. Two stickers on the jamb or the door edge: the safety certification label (GVWR, GAWR front and rear, date, VIN) and the tire-and-loading placard, which carries the payload sentence. Some trucks add a third, the "cargo capacity" sticker, for the payload alone. (567.4(c); 571.110, S4.3(a))
- "The combined weight of occupants and cargo should never exceed"
- 1,300 lb← enter this · PAYLOAD for this truck as built, and the only payload number that counts
- GVWR
- 7,850 lb← enter this · the truck’s own loaded limit
- GAWR front / rear
- 3,450 / 4,050 lb← enter this · the rear one is what a tongue overloads first
- Tire size and cold psi
- LT265/70R17 · 60 / 65 psiignore · front / rear; the pressures the GAWRs assume
Ignore: The brochure payload ("up to 2,300 lb"), which is the lightest trim with no options. The tow rating isn’t on the jamb at all; it’s in the owner’s manual towing section by engine, axle ratio and cab, and so is GCWR.
The hitch receiver and the fifth-wheel hitch
Where: A sticker or a stamping on the receiver tube itself, usually on the side facing the bumper; on a fifth-wheel hitch, a plate on the base or a stamping on the head.
- Weight carrying (WC)
- 1,200 lb tongue / 12,000 GTW← enter this · without a WDH
- Weight distributing (WD)
- 1,600 lb tongue / 16,000 GTW← enter this · with the bars; the towing page uses this rating when you tow with one
- Fifth-wheel hitch
- 4,000 lb pin / 16,000 GTW← enter this · pin rating is the one that matters
Ignore: The ball’s stamped rating and the ball mount’s rating are separate limits, and the lowest of receiver, mount and ball is the one that applies.
The battery label
Where: The top or the side of each battery. Lithium batteries print everything; lead-acid batteries often print only the group size and a cranking figure, and the amp-hours are on the maker’s data sheet.
- Nominal voltage
- 12.8 V← enter this · 12 V, or 6 V for golf-cart batteries wired in pairs
- Capacity
- 100 Ah← enter this · at the 20-hour rate; that’s the figure to enter, per battery
- Chemistry
- LiFePO4← enter this · flooded, AGM or lithium; the usable share depends on it
- Max continuous discharge
- 100 A← enter this · sizes the inverter the bank can feed; on the data sheet if not the label
Ignore: CCA (cold cranking amps) and reserve minutes, starting-battery figures that say nothing about house capacity. "Peak" discharge current, which lasts seconds.
Inverter and generator data plates
Where: The inverter: a label on the case, often the underside. The generator: a plate on the frame or under the maintenance cover, and the same figures on the first page of the manual.
- Inverter continuous output
- 2,000 W← enter this · the number to enter; some makers print it at 25 °C and it falls when warm
- Inverter surge / peak
- 4,000 Wignore · seconds only; useful for a motor start, not for sizing
- Generator rated / running watts
- 1,800 W← enter this · what it delivers all day: a "2,200" inverter generator is 1,800 rated
- Generator starting / peak
- 2,200 Wignore · the marketing number on the side of the case
- Fuel and tank
- Gas · 0.95 gal← enter this · plus gal/h at 25% and 100% load from the manual, for runtime
Ignore: VA ratings on inverter/chargers ("3,000 VA" is about 2,400 W). The big number painted on the generator.
The air conditioner’s data plate
Where: Under the rooftop shroud, on the unit’s housing (four screws and it lifts off), or on the spec sheet for the model number printed on the inside ceiling assembly.
- Cooling capacity
- 13,500 BTU/h← enter this · the size
- Rated amps / watts
- 13.5 A · 1,500 W← enter this · running draw, for the shore and generator checks
- LRA (locked-rotor amps)
- 55 A← enter this · the compressor’s start surge, which a soft start cuts by two-thirds
- Heat pump
- yes / no← enter this · a heat-pump unit heats down to about 40 °F
Ignore: Nothing on the plate is a sales figure. Read the plate itself: the shroud badge may be a series name shared across sizes.
The furnace and water-heater labels
Where: The furnace: a label on the unit behind its exterior access door, or on the inside of that door. The water heater: a label behind its exterior door beside the drain plug.
- Furnace input
- 30,000 BTU/h← enter this · the input; the calculators apply the 75% efficiency
- Water heater capacity
- 6 gal← enter this · and whether it has an electric element as well as the burner
- Water heater input
- 8,800 BTU/h← enter this · the burner rating, for propane use per shower
Ignore: The furnace’s "output" figure if the label prints both. Enter the input and let the tool derate it, so the propane page and the sizing page agree.
The tire sidewall
Where: Molded into the sidewall of every tire, small text near the bead.
- Size
- ST225/75R15← enter this · ST = special trailer; LT = light truck
- Load range
- E← enter this · the ply rating letter
- Max load
- 2,830 lb at 80 psi cold← enter this · per tire; times the tires on the axle is the axle’s tire limit
- DOT date code
- 2323ignore · week and year of manufacture; trailer tires age out at about six years regardless of tread
Ignore: The "max psi", which is the pressure for the max load and isn’t a target. The tire placard’s cold psi is the number to run, and the tire-pressure calculator (when it ships) works from your axle loads.
Tanks and cylinders
Where: Tank sizes are on the floor-plan spec sheet (the maker’s website by model year) and often on the tank-monitor panel’s label. Propane cylinders have their capacity and tare weight stamped on the collar; a motorhome’s ASME tank has a plate on the tank with its water capacity.
- Fresh / gray / black
- 52 / 82 / 45 gal← enter this · nominal; usable is a little less on every tank
- Cylinder capacity
- 20 lb← enter this · the propane it holds; "TW 17" beside it is the empty weight
- ASME tank capacity
- 20 gal (water)← enter this · filled to 80%, which the calculators apply
Ignore: A monitor panel’s ⅓ / ⅔ / full lights. They read the sensor strips, which foul; the tank-duration page counts days from what you use.
What if a label is missing or unreadable?
The yellow cargo label is the one that matters legally, and it's tied to the VIN: the manufacturer's customer service line will read it back to you or mail a replacement, and many post the build sheet online. A truck's stickers are on the safety certification label by law; a dealer can pull the build from the VIN too. For appliance plates, the model number printed on the unit (AC ceiling assembly, furnace door, inverter case) plus the maker's spec sheet gives you the same figures. What you can't replace with a phone call is anything that depends on how you load it: tongue weight, axle loads and the loaded trailer's weight. For those the scale is the label. Dealer-installed gear and everything you've added since is on no label at all; the RV loaded weight calculator adds it to the label's figures.
The three lines people enter wrong
- Payload from the brochure. The brochure's "up to" payload is for the lightest configuration, and every option on your truck comes out of it, so the sentence on the jamb sticker is the figure to enter. Payload is the check that fails first in the towing checks.
- Generator or inverter peak watts. The big number is seconds of surge. Enter rated (running) watts for the generator and continuous watts for the inverter; the calculators add the surge back where it belongs, and the generator size calculator sets it against the air conditioner's start.
- Furnace output instead of input. Most labels print input; if yours prints both, enter input. The propane and heater-sizing pages apply the efficiency themselves, and entering output makes them disagree with each other.
Sources
- 49 CFR § 571.110, Tire selection and rims and motor home/recreation vehicle trailer load carrying capacity information for motor vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or less, Legal Information Institute, Cornell Law School (eCFR text): the yellow cargo labels (S9.3.4, S9.3.5), their location (S9.3.3), full propane in UVW and water as cargo (S9.3.2), the tire placard (S4.3, S4.3.5), dealer-added weight (S10)
- 49 CFR § 567.4, Requirements for manufacturers of motor vehicles, Legal Information Institute, Cornell Law School (eCFR text): the certification label: manufacturer, date, GVWR, GAWR, VIN; on a trailer, the forward half of the left side