Why does towing at 7 mpg burn extra gas on every soft tire — and why is that gas the cheapest thing a soft trailer tire will cost you?
Gas is $4.49 this week, diesel $6.48, and RV owners are shortening trips, staying put, or towing anyway and wincing at every pump. Six tires under a travel trailer and its tow vehicle, all losing pressure between trips. Two families, one habit, and the number that decides whether the trip costs $1,200 or $3,000.
THE NUMBER FIRST — SO YOU CAN CHECK IT
Low tires burn more fuel — and towing multiplies it. The U.S. Department of Energy: about 0.2% more fuel for every 1 psi low, 0.6% on average, up to 3% when tires are badly low. At 7 mpg towing, a percent is a lot of gallons.
Trailer tires go soft sitting. About 1 psi a month with no puncture (Michelin). A trailer stored from October to April leaves at 6–8 psi under — and trailer tires need 50–65 psi, not 35, so the light in the truck tells you nothing about them.
Low pressure is a leading cause of trailer blowouts. Good Sam Roadside lists under-inflation first among the causes; heat and load make it worse, and towing is nothing but heat and load. Michelin: a tire run 20% under lasts about 20% less.
Sources at the bottom of the page. We'd rather you check than believe us.
Every October the Hendersons tow to Arizona. This year they nearly didn't. At 7 mpg and $4.49 the fuel alone is about $1,200 each way, and their forum is full of people saying “we'll stay put this year.” They went — but they did the math first, and the math found something.
The trailer had sat since Labor Day. Four trailer tires at 46–48 psi on tires rated 65. The Suburban's rears, which carry the tongue weight, at 31 on a 38 sticker. Nothing flat. Nothing lit. Just every tire under, on the heaviest, hottest, longest drive of the year.
Honest version: on a camper, the gas saving is real but modest. Gas is the reason you finally check. The blowout you don't have is what checking was for.
DAN AND MARIA, 44 & 41, OHIO — THE STORY THAT ISN'T ABOUT GASDan checked the truck's tires before the July trip because the truck has a light. He didn't check the trailer's, because the trailer doesn't, and the only pump on the way stops at 50 psi anyway. One tire was at 38 on a 65. Two hundred miles into Kentucky, in 94-degree heat, loaded with a week of water and gear, it came apart at 65 mph.
The trailer stayed upright. The tire took the fender, the skirt, the water line and a wiring loom with it. Roadside took two hours and forty minutes to reach an interstate shoulder with two kids in the truck. The repair was $1,840. The campground didn't refund the first two nights. Maria drove the rest of the trip at 55 watching the mirror.
A trailer tire never warns you. It goes from “looks fine” to gone, and it picks the hot, loaded, fast part of the day to do it.
“The gas station pump does it.”
The pump at the gas station is built for cars. Most stop at 50 psi; trailer tires want 50–65 and some 80. So you pay $2, wait for it to time out at 50, and leave a trailer tire under-inflated with a receipt. The good pump is in town, twenty miles the wrong way from the site, and out of order one time in three.
“A percent or two of gas isn't worth a gadget.”
On gas alone, fair — $18–37 each way on a big trip, maybe $100 a season. That's the price of the tool, back in the first year, from a habit that takes ten minutes on departure morning. But the honest reason RV owners check pressure isn't the $100. It's that the same ten minutes is the difference between the Hendersons' trip and Dan's.
“I'll check them when I hitch up.”
With what? A pencil gauge tells you they're low and gives you nothing to fix it with at the storage lot. A shop compressor is at home. The pump that reaches 65 is across town. Departure morning is the one time you have the least patience for a detour — which is why trailer tires leave low year after year.
The belief that changes
Tire pressure on a trailer isn't a maintenance chore for the mechanically inclined. It's the ten-minute departure ritual that, at today's fuel prices, pays for itself in gas — and that at any fuel price is the cheapest insurance a travel trailer can have.
Real tire, real time. Set the number from the sidewall, press start, it stops itself. Trailer tires up to 65 psi; if yours are rated higher, email us first.
Pump in town, pencil gauge, or the door pocket — settled honestly
The gas-station pump: stops at 50, $2 a go, and it's not at the campsite or the storage lot.
A pencil gauge: tells you the bad news and can't do anything about it.
The door pocket: hose on, set 65, press start. It reads the tire, fills to the number and stops itself, so you can't over-inflate a trailer tire either. Six tires, about ten minutes, at the site, before you hitch. The same unit charges the phones and starts the tow vehicle when a weekend of dome lights has flattened it.
Departure morning, before the coffee's finished: six tires, one hose, the screen shows the pressure they're at and the number they set. Fifty-five minutes of towing later they're on the interstate at the speed limit, not at 55 watching the mirror. The fuel bill came down a little. The thing they don't talk about is the blowout they didn't have.
The part they didn't buy it for: Sunday at a state park in New Mexico, the Suburban clicked after two nights of dome lights and phone chargers. Red clip, black clip, green light, key. Three minutes, then checkout at eleven, no roadside, no late fee. Same unit, same door pocket.
The RV owners still travelling at $4.49 a gallon aren't the ones with the most money. They're the ones who stopped towing on soft tires — because the pump lives in the door pocket, not across town.
What it won't do
It won't make fuel cheap. It stops the tow vehicle and the trailer burning the 1–3% you're paying for nothing, and it stops a soft trailer tire becoming a blown one.
It won't charge the trailer's house battery. That's the converter, the alternator or solar. It starts the vehicle that tows.
Trailer tires rated above 65 psi: email us before you buy and we'll confirm for your size.
THE DEVICE IN THE HENDERSONS' DOOR POCKET
The JumpAir Pro.
A tire inflator that fills to the number you set and stops itself — trailer and tow vehicle — and a jump starter with clamps that cannot spark, in one unit that fits in a door pocket. Everything it does and doesn't do, including the awkward bits, is written plainly on the product page.
See how it works →Sources. Fuel economy per psi and the 0.6%–3% figure: U.S. Department of Energy, fueleconomy.gov. 1 psi a month and the 20% wear figure: Michelin. Low pressure as a leading cause of blowouts: Good Sam Roadside. 25%-under tires three times as likely to be the critical pre-crash event: NHTSA, DOT HS 811 617. Fuel prices: AAA national averages, September 26, 2026 (regular $4.49, diesel $6.48). Towing mileage and “we'll stay put this year”: RV owners' forum threads, April 2026. The Hendersons, Dan and Maria are composites of RV owners we've spoken to and read; their numbers use the sources above.