[PRODUCT NAME — tire inflator]
I use this all the time on my cars.
Will It Get Stuck? — Off-Road Ground Calculator
The gun is buildable. Italy has fielded a wheeled tank since 1991. The ground is the problem: the eight-wheeled armored vehicles in the study fail on swamp ground, and the Centaur has four tires.
Your vehicle
Weight divided by the rubber actually on the ground
Ground pressure is your vehicle’s weight divided by the tire patch. Fill in what you measure. The list can load a published curb weight. It cannot load a footprint. The Centaur button only loads a tire count, because no weight or footprint was published.
ground pressure (psi) = weight (lb) ÷ contact area (in²)
contact area = tires × patch width × patch length
—psi
— tires × — in × — in = — in²
— lb ÷ — in² = —
Enter a weight, a tire count, and a patch. Each one has to be greater than zero.
This is not a precise ground pressure. The list loads one published empty weight, and it sets the tire count to 4. Manufacturers do not publish the patch of tread on the ground, so this page will not guess it. The result stays blank until you measure that patch.
The patch on the ground, in inches
These fields stay blank on purpose. No manufacturer publishes this rectangle, so a precise ground pressure cannot be loaded. A tire size is not the patch. The psi on the door-jamb sticker is the air in the tire, not the pressure on the ground. Measure it. This page will not guess.
How to measure your tire’s footprint
- Mark where the tread meets the ground at the front of the tire and at the back. Chalk or tape.
- Measure between the marks. That distance is the patch length.
- Measure the width of tread actually touching the ground. That is the patch width.
For the weight, use curb weight from the owner’s manual or the manufacturer spec. The door-jamb sticker’s GVWR is the maximum loaded weight, not the empty weight.
If you let air out to watch the footprint change, re-inflate to the pressure on the door-jamb sticker before driving.
Your vehicle. Enter curb weight and the patch you measured. This page does not check those numbers.
Ground pressure scale
0 psi
20 psi
Two published ground pressures are on this scale: M1A1 at 13.8 psi and M1A2 at 15.4 psi. Your result is plotted against them. If it sits past 1,000 psi the axis stops and the number is marked off scale. Tire inflation, including the bicycle line and the 90 / 25 pair, is not ground pressure and is not plotted. Swamp strength is in its own section, in its own unit, and it is not on this scale.
How the number was reached
- Divide weight by the patch. Ground pressure is weight divided by the rubber on the ground. The patch is a width times a length. Multiply by the number of tires. The calculator is that division.
- Two tanks that print the figure. General Dynamics prints the M1A1 at 13.8 psi and 67.6 tons. The M1A2 is a different vehicle: 15.4 psi, curb weight 69.54 tons. Both are ticks on the scale. Neither is a preset.
- The wheeled tank, and the fictional one. IDV lists the Centauro II at a gross vehicle weight of 30,000 kg, with central tire inflation, and does not list a ground pressure. The Centaur is four tires and has no published weight. Its button does not invent one.
- 90 and 25 are air in the tire. In the study, an IDV eight-wheeler goes from 90 psi on the road to 25 psi in mud. Those are inflation pressures. They are not the pressure the vehicle puts on the ground.
Soft ground: why psi isn’t the whole story
The pressure a vehicle puts down is not the test the paper runs. Vehicle Cone Index is the strength the ground has to offer before that vehicle can make one pass. Both can be written in the same unit. They point in opposite directions. Nothing in this section belongs on the calculator scale.
A 2017 paper from Romania’s Military Technical Academy ran the numbers on six eight-wheeled armored vehicles. Not a field test. Formulas, fed with published data sheets. The ground they asked about was muskeg, the wet soil across large parts of Canada and Alaska. Muskeg offers a cone index of 40.
Scroll sideways for the full row.
| Vehicle in the study | Strength the ground must offer | Muskeg offers | Result |
|---|---|---|---|
| Boxer | 96 | 40 | Fails |
| Stryker | 63 | 40 | Fails |
| IDV eight-wheeler (SuperAV), same tire family as the Centauro II. Not the Centauro’s own figure. | 70 | 40 | Fails |
The authors’ own line is that only tracked vehicles stand a chance, because the pressure under a track is lower. A US Army field manual says the same thing about organic soil: wheeled vehicles usually cannot travel it.
Letting air out of the tires does move the result on clay and silt, by about a fifth to a third. On muskeg the formula has no slot for tire pressure. Airing down does not change those three failures.
The Centaur has four tires. Every vehicle in that table has eight. Half the patches, same kind of problem, and no four-tire cone index was calculated. The script doesn’t invent one. The Centaur gets across this wall in fiction the only way a wheeled tank can: it is light, because a helicopter carries it, and it is not wearing tank armor. Off pavement, that is a truck with a cannon.
Assumptions log
This is the work. If a Centaur cell says the value was not used, that is the result, not a missing edit.
Ground pressure
Scroll sideways. This table does not contain cone-index figures.
| Assumption | Value used | Source | Confidence |
|---|---|---|---|
| Layout | Wheeled, not tracked | Gears of War Wiki, Centaur | Verified |
| Tire count | 4 | Visual count of the studio render on the Centaur wiki page. The wiki sentence does not say “four tires.” | Bounded Guess |
| Contact patch shape | A rectangle: width × length. A real patch is rounded, so this slightly overstates area and understates psi. | This page’s method. Not a measured outline. | Bounded Guess |
| Visitor weight and patch | Whatever is typed in. The page does not verify it. | Entered on this page by the visitor. | Not verified |
| Example curb weights | One published empty weight for the named configuration. Four tires. Footprint not loaded. Not a ground pressure. | Jeep spec sheet, Toyota Tacoma brochure, Chevrolet press specs, GMC press specs, Tesla owner’s manual | Verified weights |
| Centaur mass | Not used. Nothing published. | Centaur, High Velocity Main Cannon, and Delta’s Centaur wiki pages | Verified |
| Centaur ground pressure | Not estimated | Same absence. IDV also prints no ground pressure for the Centauro II. | Verified |
| Centaur speed and caliber | Not used. Nothing published. | Centaur wiki page | Verified |
| King Raven vehicle payload | Not used. Nothing published. | Delta’s Centaur wiki page. A personnel load is not a slung-tank weight. | Verified |
| M1A1 ground pressure | 13.8 psi | GDLS M1A1 flyer | Verified |
| M1A1 weight | 67.6 tons. Spoken as sixty-seven. | GDLS M1A1 flyer. Script rounds it. | Verified |
| M1A2 ground pressure | 15.4 psi | GDLS M1A2 flyer. A different variant from the M1A1. | Verified |
| M1A2 weight | 69.54 tons, curb weight | GDLS M1A2 flyer | Verified |
| Centauro II gross vehicle weight | 30,000 kg. Not applied to the Centaur. | IDV spec sheet | Verified |
| Centauro II ground pressure | Not published | IDV product page and the CIO PDF | Verified |
| Derived Centauro contact pressure | Withdrawn. Not used. | Fact-check, 2026-09-07. The tire-catalogue patches were not real. | Verified |
| 90 psi road, 25 psi mud | Tire inflation on the paper’s IDV eight-wheeler. Not ground pressure. Not the Centaur. | Roșca and Ciobotaru, 2017, Table I | Verified |
| Bicycle tire | Spoken as “less than a bicycle tire.” No single psi used. | Script, chapter 5. A check used an inflation range of 65–130 psi. That range is not plotted. | Bounded Guess |
Soil strength — not ground pressure
Separate table. These figures are the bar the dirt has to clear. Do not read them against 13.8 or 15.4.
Scroll sideways.
| Assumption | Value used | Source | Confidence |
|---|---|---|---|
| What the cone index measures | Minimum soil strength for one pass. Not the pressure the vehicle exerts. | Roșca and Ciobotaru, 2017. Script chapter 6. | Verified |
| Muskeg reference soil | Cone index 40 | Same paper | Verified |
| Boxer, muskeg, one pass | 96 | Table II, row VCI1MK | Verified |
| Stryker, muskeg, one pass | 63 | Table II, row VCI1MK | Verified |
| SuperAV, muskeg, one pass | 70. Same manufacturer and tire family as the Centauro II. Not a Centauro result. | Table II and Table I. Tire listed as 14R20. | Verified |
| Airing down, on clay and silt | About a fifth to a third. The paper’s fine-grained spread is about 19 to 31 percent. | Script chapter 6. Paper’s own table, checked. | Verified |
| Airing down, on muskeg | No change. The muskeg formula has no tire-pressure term. | Same paper. The authors say deflection does not move this result. | Verified |
| How those figures were made | Calculated from data sheets. Not measured in a swamp. | Paper method. Script line: “ran the numbers.” | Verified |
| Army doctrine | Wheeled vehicles usually cannot travel most organic soil. | US Army FM 5-430-00-1 | Verified |
| Four tires against an eight-tire study | Qualitative only. No four-tire cone index was calculated. | Script chapter 6 | Verified |
Sources
Ground pressure and the machines
- General Dynamics Land Systems, M1A1 flyer. Used for 13.8 psi at 67.6 tons. PDF
- General Dynamics Land Systems, M1A2 flyer. Used for 15.4 psi at a curb weight of 69.54 tons. Kept as its own variant. PDF
- IDV, Centauro II product page. Used for the 30,000 kg gross vehicle weight, the tire and inflation system, and the confirmed absence of a ground-pressure figure. IDV
- CIO, Centauro II data sheet (October 2024 PDF). Used to confirm the 14.00R20 XZL/XML tire and that ground pressure is still not printed. PDF
- Gears of War Wiki, Centaur. Used for wheels instead of tracks, four-wheel steering, and the absence of mass, speed, and caliber. Wiki
- Gears of War Wiki, Delta’s Centaur. Used for the King Raven drop, and for the absence of a vehicle payload. Wiki
- Jeep, 2025 Wrangler specifications. Used for the Rubicon 4-door, 3.6-liter manual, base weight of 4,575 lb. Not a footprint. PDF
- Toyota, Tacoma brochure. Used for the TRD Off-Road Double Cab, 5-ft bed, 4x4, i-FORCE, curb weight of 4,630 lb. Not a footprint. PDF
- Chevrolet press specs, 2025 Silverado 1500. Used for the Crew Cab, 4WD, 2.7-liter, 5-ft 8-in box, base curb weight of 4,950 lb. Not a footprint. Chevrolet
- GMC press specs, 2025 Sierra 1500. Used for the same cab, engine, and box, base curb weight of 4,950 lb. Not a footprint. GMC
- Tesla, Cybertruck owner’s manual. Used for the Dual Motor all-wheel-drive curb mass of 6,537 lb. Tesla says it can vary with options. Not a footprint. Tesla
Soil strength
- Petru Roșca and Ticușor Ciobotaru, “8×8 Armoured Personnel Carrier Mobility Evaluations Using Vehicle Cone Index,” MTA Review Vol. XXVII, No. 2, December 2017. Used for the muskeg row, the 90-to-25 inflation pair, and the finding that wheeled-armor brochures skip the mobility number. ResearchGate
- US Army FM 5-430-00-1, Planning and Design of Roads, Airfields, and Heliports in the Theater of Operations. Used for the doctrinal line on wheeled vehicles and organic soil. Read from a public mirror, not an army.mil original. GlobalSecurity mirror
Watch the video
The spoken version of this page is the video. The link is not posted here yet.
[VIDEO URL]
Gear I actually use
Airing a tire down grows its footprint, the same idea as in the video. These are what I keep for my own cars: an inflator to air back up, and tire sealant for emergencies.
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[PRODUCT NAME — fix-a-flat]
I carry this for emergencies.
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