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Tire pressure is the air support that lets the tire carry vehicle weight, keep a stable contact patch, and manage heat while rolling. Too little pressure can increase flex and shoulder wear, while too much can reduce compliance and shift the load toward the center of the tread. This calculator estimates cold front and rear targets from the vehicle load you enter and keeps those targets anchored to either a door-placard baseline or a vehicle-class preset.
The tool is built for the ordinary decisions drivers actually make: a lightly loaded commute, a family road trip, a winter morning, or a cargo-heavy day that changes rear-axle demand. You can enter curb weight, passenger count, average passenger weight, cargo, front and rear tire widths, front axle share, road surface, driving priority, and tire setup. The result is not one generic pressure number. It is a paired recommendation for the front and rear axles, with a target band, a safe window, and a chart that shows how the recommendation moves as total loaded weight changes.
Placard mode is the most exact path when you have the manufacturer’s cold inflation values from the door jamb sticker. Class-preset mode is a fallback for rough planning when you do not have those values in front of you. In that preset path the calculator starts from built-in baselines for compact cars, sedans, wagons and CUVs, SUVs, pickups, and EV or performance vehicles, then adjusts those baselines for load, tire width, and the factors you selected for road surface, efficiency, comfort, or handling.
The split between front and rear matters because many vehicles do not carry the same load on both axles, and some use different tire widths front and rear. The calculator makes that visible instead of hiding it inside one average figure. It also gives each axle a note, a target in psi and bar, a softer target band for practical adjustment, and a harder safe window that can be tightened further if you supply a sidewall maximum as a ceiling.
This is still a planning tool, not a substitute for the vehicle manufacturer’s exact load tables, towing guidance, or alternate placard rows for special tire sizes. Its strongest use is to help you reason from the correct reference point: cold pressure, axle load, and the placard or manual first. If the tool and the placard disagree, the placard should win.
The first decision is where your baseline comes from. If the door placard is available, use it. That preserves the manufacturer’s intended cold front and rear values for your exact vehicle and tire specification, and the calculator then adjusts around that known starting point. If the placard is not available, the class presets provide a reasonable planning baseline so you can still see how passenger load, cargo, and front-rear balance are likely to shift support needs.
The second decision is how to describe the load. Curb weight establishes the empty vehicle, passenger count and average passenger weight add live load, cargo adds trunk or bed weight, and the front axle share tells the tool how that total is distributed. A higher rear load or a lower front-share percentage will usually move the rear target upward. Tire widths also matter because the preset path assumes a 235 mm reference width and adjusts support slightly when the actual section width differs.
The third decision is what kind of bias you want around the baseline. Rough roads and comfort pull the estimate slightly downward, while highway use, efficiency, handling, winter conditions, and reinforced casings nudge it upward. Those are not dramatic jumps. They are small multipliers that change how firmly the tire supports the same load. That makes the tool useful for comparing two nearby setups rather than treating every driving situation as identical.
| Situation | Inputs that matter most | Outputs to compare |
|---|---|---|
| Routine cold-pressure check | Placard front and rear values, current load, front axle share | Front and rear targets, target band, summary note |
| Heavier family or cargo trip | Passenger count, average passenger weight, cargo weight | Rear target shift, safe window, Car Pressure Map trend |
| Comparing comfort and handling bias | Surface, priority, tire setup | Target psi difference and the resulting target band |
| Checking a tire-sidewall ceiling | Front or rear tire max in psi | Safe window and whether the target gets clamped |
The package uses two baseline systems. In class-preset mode it starts from built-in front and rear cold pressures plus a reference vehicle weight. In placard mode it uses the front and rear values you enter from the door sticker and treats the vehicle’s current curb weight plus one average passenger as the baseline loaded condition. From there, it allocates total loaded weight across the front and rear axles using the front-share percentage and then adjusts each axle target separately.
Load changes are translated into pressure through a bounded load factor based on the difference between the current axle load and the baseline axle load. In preset mode, width also affects the estimate through a 235 mm reference, so narrower tires tend to push the target up and wider tires tend to pull it down. Surface, priority, and tire setup apply additional multipliers, all kept within modest bounds so the tool stays close to a realistic cold-pressure neighborhood instead of making extreme jumps.
Once the raw target is calculated, the tool clamps it into a safe window. In placard mode that window runs from 8 psi below the baseline to 14 psi above it, subject to any lower sidewall-maximum ceiling you enter. In preset mode most vehicles use a 30 to 44 psi window, while pickups and EV or performance vehicles use a slightly firmer minimum or higher rear ceiling. The displayed target band then expands around the final target by either 2 psi or 5%, whichever is larger.
| Vehicle class | Front baseline | Rear baseline | Reference weight |
|---|---|---|---|
| Compact / hatchback | 32 psi | 32 psi | 1300 kg |
| Sedan | 33 psi | 33 psi | 1500 kg |
| Wagon / CUV | 34 psi | 36 psi | 1700 kg |
| SUV | 35 psi | 37 psi | 1900 kg |
| Pickup (light load) | 36 psi | 40 psi | 2100 kg |
| EV / performance | 38 psi | 40 psi | 2000 kg |
| Control | Options in the package |
|---|---|
| Surface | Highway / steady 1.02, City / mixed 1.00, Rough roads 0.97, Winter / cold 1.01 |
| Priority | Comfort 0.97, Balanced 1.00, Fuel or EV efficiency 1.02, Handling / high-speed 1.04 |
| Tire setup | All-season 1.00, Summer 1.01, Winter 1.02, XL / reinforced 1.04 |
The outputs are designed for both quick reading and record keeping. You get an axle table with load, target, range, safe window, and copy buttons; a Car Pressure Map chart with image and CSV export; and a JSON payload containing the original inputs plus the computed axle values. The chart is especially useful because it shows front and rear boundary lines across a span of loaded weights rather than only at the current point.
The target is the calculator’s best single-number recommendation for that axle under the inputs you entered. The target band is a practical working range around that target, while the safe window is the harder boundary the tool refuses to cross after baseline and sidewall-maximum rules are applied. If the note says the result was clamped, the raw estimate wanted to go outside that safe window and the final recommendation has been pulled back to the nearest allowed edge.
| Output | What it means |
|---|---|
| Target | The final cold pressure recommendation for that axle after all load and bias adjustments. |
| Range | A working band around the target for small practical adjustments, shown in psi and bar. |
| Safe | The window the package allows after baseline rules and any sidewall-maximum ceiling are applied. |
| Axle note | A short interpretation of where the target sits, such as many-placard range, soft ride, or high-load support. |
| Summary note | A one-line view of loaded weight, front-share percentage, baseline type, and front-rear spread. |
An SUV preset starts at 35 psi front and 37 psi rear with a 1900 kg reference weight. If you enter 1900 kg curb weight, four 75 kg occupants, 100 kg of cargo, 235 mm tires front and rear, a 55% front share, and balanced city driving, the total loaded weight becomes 2300 kg. In that setup the calculator pushes the front target to about 39.4 psi and the rear to about 40.6 psi, making the rear roughly 1.2 psi firmer because it is carrying more of the added trip load.
A pickup preset starts at 36 psi front and 40 psi rear. With a heavier bed load, the rear target can climb into the low 40s, which is reasonable for support but still must stay inside the casing limit of the tire you actually have mounted. If you enter a rear tire maximum that sits below the raw estimate, the tool clamps the rear result to that ceiling and marks the note accordingly, which is useful when you want to keep a planning estimate from drifting past the tire’s own cap.
The door placard or owner’s manual should be the primary source because those values are matched to the vehicle and tire specification. Use the class presets only when you need a rough planning baseline and the placard is not available.
Because axle loads differ. The front and rear may also use different tire widths, and the preset classes themselves are not always symmetrical. Separate targets keep support aligned with the load each axle actually carries.
No. In this calculator the sidewall maximum is only an optional ceiling that can clamp the safe window. It is not the recommended everyday cold target for normal driving.
No. The calculator does not know your exact manufacturer load table, alternate placard rows, or trailer-specific instructions. It is best used as a structured estimate around the cold-pressure rules you already know from the placard and manual.