Tire Pressure by Actual Axle Weight
Your door-jamb sticker assumes you're loaded to max GVWR. Match your cold tire pressure to what your rig is actually carrying today, using a real axle-scale weight.
Front axle Axle 1
Weigh this axle alone at a CAT scale, then read the two numbers molded into the tire's sidewall.
Rear axle Axle 2
Same process for the rear — if you run dual rear wheels, set "Tires per side" to Dual so the load splits four ways instead of two.
How the math works (constants & formulas)
- Load per tire:
axle weight ÷ (2 × tires per side)— a single-axle-single-tire setup splits the weight two ways (left/right); dual rear wheels split it four ways. - Load fraction:
load per tire ÷ tire's max load rating— how much of the tire's rated capacity you're actually using. - Estimated pressure:
load fraction × tire's max pressure, rounded up to the nearest 5 psi (we never round down — that would under-inflate). This assumes a roughly linear load/inflation relationship, which real tire manufacturer load tables approximate closely but not perfectly. - Safety clamp: the result is never allowed below your door-jamb minimum pressure, and never above the tire's own max pressure, regardless of what the raw math says.
- For highway speeds in hot weather, many RVers add 3–5 psi above the calculated minimum as a cushion — this calculator shows the floor, not that cushion, so add it yourself if you're planning a long, hot highway day.
- This is a simplified linear approximation, not the tire manufacturer's actual published load/inflation table (available from the Tire and Rim Association or the tire maker directly) — cross-check against that table before a long trip if you want the precise, non-linear number.
Before you air up
Safety first: always check pressure when tires are cold — not driven on for at least 3 hours, or less than 1 mile. Never go below your vehicle's stated door-jamb minimum regardless of what this calculator suggests, and always inspect tires for cracks, uneven wear, bulges, and DOT date (tire age) before a trip — those failures have nothing to do with pressure. See our disclaimer.
Gear that pairs with this calculator
S'more's Outdoors may include Amazon affiliate links; if you buy through one, we may earn a commission at no extra cost to you. S'more's Outdoors is an independent publisher and is not affiliated with, sponsored by, or endorsed by any tire manufacturer, vehicle maker, brand, or retailer whose products or trademarks appear on this page; all product names and trademarks are the property of their respective owners.
FAQ
Why not just use the door jamb pressure?
The door-jamb (or trailer frame) sticker gives you one pressure calculated for the vehicle loaded up to its rated GVWR or GAWR — the heaviest it's ever supposed to be. Most trips are lighter than that, so running the max-load pressure on a lightly loaded axle over-inflates the tire: harsher ride, faster wear down the center of the tread, and less contact patch for traction and braking. The sticker pressure is a safe ceiling, not necessarily the right number for how you're loaded today.
What if my front and rear tires are different sizes or ratings?
That's normal on trucks and trailers with dual rear wheels or different tire specs front to back, which is why this calculator runs the front and rear axle separately with their own tire's max pressure and max load rating. Always use the load/pressure numbers molded into that specific tire's sidewall, not the other axle's tire, even if they look similar.
Is it safe to run less than the tire's max pressure?
Yes, as long as you never go below two floors: the tire manufacturer's minimum pressure for the load it's actually carrying, and your vehicle's door-jamb minimum. Running a properly inflated tire below its max-pressure rating, but above those floors, is exactly how load/inflation tables are designed to work — max pressure corresponds to max load, and lower loads are rated for proportionally lower pressures. What's not safe is guessing low without doing this math, since under-inflation for the actual load causes overheating and sidewall flex that can lead to a blowout, especially at highway speed on a long, hot drive.
How do I find my tire's max load and pressure rating?
It's molded directly into the tire sidewall, typically as "Max load XXXX lb at YYY PSI cold." It is on the tire itself, not the vehicle's door-jamb sticker — the door-jamb sticker gives the vehicle manufacturer's recommended pressure for the tire size they specified, which is a different number used for the safety-floor check in this calculator. If your tires have been replaced with a different size or load range than the vehicle shipped with, use the new tire's own sidewall numbers here, and note that your door-jamb sticker may no longer reflect the correct minimum.