The Four-Corner Weigh-In

How accurate RV weights + smarter speed save fuel, tires, and repair bills

Why “close enough” weight guesses cost you money

Most owners air up the tires to a round number, set the cruise to 68–72 mph, and hope for the best. The RV four-corner weigh tells you the real load on each wheel. That lets you set PSI from the manufacturer’s RV tire load chart, even out-of-side-to-side cargo, and then derate your cruising speed to the sweet spot where heat, rolling resistance, and fuel burn all drop. The result: tangible fuel savings, cooler tires, smoother handling, and far fewer roadside dramas.

What you can save:

• Fuel: Typically 6–12% by pairing correct PSI with a 5–8 mph speed reduction.
• Tires & damage avoidance: A single prevented blowout can avoid $300–$1,000+ in rubber, wheel well damage, wiring, trim, and downtime.
• Brakes, bearings, and suspension: Cooler, happier components last longer (soft savings, real money).

Step-by-step: The Four-Corner Weigh-In Method

1. Weigh all four corners (or both duals on each axle).
   • Best: Mobile RV rallies/shops with individual scale pads.
   • Backup: A three-pass CAT scale (left/right bias estimated). If you must estimate, add a 10% safety margin to the heavier side.
2. Find the tire manufacturer’s load/pressure chart for your exact size and load range.
   • Match the heaviest corner on that axle to the minimum PSI that supports it.
   • Add a small operational buffer (often +5 PSI) for temp swings and gauge variance—but never exceed wheel or valve-stem ratings.
3. Rebalance your cargo.
   • Move tools, water, batteries, and bulky gear toward the lighter side.
   • Even 40–80 lb shifted across the aisle can reduce scrub, sway, and shoulder wear.
4. Derate your highway speed.
   • Lock in a cruise around 60–63 mph (or the speed where your engine runs lowest BSFC in top gear).
   • Heat drops, rolling resistance falls, and your tires live a longer, quieter life.
     
     
5. Record and re-check.
   • Make a windshield card: “Front: __ PSI | Rear: __ PSI | Max Cruise: 63 mph | Next Weigh Date: __”
   • Re-weigh after big changes (full water, new tools, bikes, solar batteries, etc.).

Quick math: what 6–12% fuel savings looks like

• Trip: 5,000 miles
• Current: 9 mpg, fuel $3.75/gal → 556 gallons = $2,085
• After weigh-in + speed derate: 9.6–10.1 mpg → 490–521 gallons = $1,838–$1,955
• Savings: $130–$247 this trip alone, plus tire life and fewer emergencies.

Pro details most people miss

• Motorhome PSI is axle-specific. You can (and often should) run different pressures front vs. rear. Trailers are Tire Size Specific.
• Duals care about match. If you run duals, keep tire circumference and PSI closely matched to avoid overloading one side.
• Temperature matters. Check cold PSI at roughly the same morning temp; expect ~1–2 PSI change per 10°F.
• Valve stems & wheels have ratings. Don’t push PSI beyond the wheel or stem spec—upgrade if needed.
• TPMS is a tool, not a plan. It warns you after things heat up. Correct corner weights prevent the heat in the first place.

Common mistakes (and easy fixes)

• Guessing PSI from a forum post → Fix: Always use the exact RV tire load chart for your tire brand/size/load range.
• Inflating to sidewall max as a cure-all → Fix: Sidewall max is a limit, not a goal. Aim for chart-derived PSI + small buffer.
• Trailer tires should always be at Max Tire Pressure.
• Ignoring side-to-side bias → Fix: Move heavy items toward the light side; re-weigh.
• Driving 70+ to “make time” → Fix: A steady 62–63 often arrives within minutes of a faster run once you add fuel and stop time—and it saves cash.

The 20-minute driveway routine (between official weigh-ins)

1. Air to your last chart-based PSI.
2. Use a quality digital gauge; verify with a second gauge quarterly.
3. Do a slow walk-around: tread/shoulders even? caps tight? valve stems intact?
4. Check torque on lugs per schedule.
5. Confirm your Max Cruise reminder on the dash.

Safety and legality

• Never exceed GAWR (Gross Axle Weight Rating) or GVWR.
• If the four-corner weigh pushes you close to limits, shed cargo or consider higher-capacity tires/wheels only within axle and wheel ratings.
• For propane, avoid prolonged high-heat runs; speed derating helps keep that front bay cooler, too.

Conclusion for The Smart RVer

“Today’s Money Saving Tip is the Four-Corner Weigh-In. Weigh each wheel, set PSI from your tire’s load chart, rebalance that cargo, and then cap your cruise around sixty-two. Most RVers see 6–12% better fuel economy, cooler tires, and far fewer blowouts. We’ll help you pick the right gauge, TPMS, and valve stems so your next trip is safer and cheaper.”