Enter Vehicle and Motion Data
Example Data Table
| Case | Mass | Wheelbase | CG from front | CG height | Long g | Lat g |
|---|---|---|---|---|---|---|
| Daily sedan | 1500 kg | 2.75 m | 1.25 m | 0.55 m | 0.20 | 0.35 |
| Heavy braking | 1600 kg | 2.80 m | 1.20 m | 0.58 m | -0.80 | 0.10 |
| Loaded van | 2300 kg | 3.20 m | 1.55 m | 0.85 m | 0.10 | 0.25 |
Formula Used
Rear static load = W cos(θ)xcg / L + W sin(θ)h / L
Longitudinal transfer = m ax h / L
Lateral axle transfer = m ay h rollShare / track
Wheel normal force = axle load / 2 ± lateral axle transfer / 2
Maximum friction force = μ × wheel normal force
Here, W is weight, L is wheelbase, xcg is center of gravity distance from the front axle, h is center of gravity height, θ is road grade, ax is longitudinal acceleration, ay is effective lateral acceleration, and μ is tire friction coefficient.
How to Use This Calculator
- Enter vehicle mass, wheelbase, track widths, and center of gravity data.
- Add cargo mass and its position if payload changes the balance.
- Set acceleration, braking, cornering, slope, and aero conditions.
- Enter tire friction and drive or brake force demand.
- Press the calculate button and review each wheel load.
- Download the CSV or PDF file for records.
Understanding Wheel Forces
Wheel force is the load carried by each tire. It changes every time the vehicle moves, turns, climbs, brakes, or carries cargo. A parked vehicle may look balanced. Yet the loads are rarely equal. Engine position, passenger weight, fuel, batteries, and tools all shift the center of gravity. This calculator estimates those changes with a practical vehicle model.
Why Each Wheel Matters
Tires create grip through normal force. More vertical load usually allows more traction. Yet the relation is not perfectly linear. A tire can also overheat or lose grip when it carries too much load. Low load is risky too. It can make a wheel lock, spin, or lift during hard motion. That is why wheel-by-wheel results are useful.
Static Load Distribution
Static load depends on total weight, wheelbase, and center of gravity position. If the center of gravity is nearer the front axle, the front wheels carry more force. If cargo is placed near the rear, the rear wheels gain force. A slope also changes the balance. An uphill grade shifts more load to the rear. A downhill grade shifts more load forward.
Dynamic Load Transfer
Acceleration and braking move load between axles. During acceleration, inertia transfers load rearward. During braking, the front tires gain load. The size of this transfer depends on mass, acceleration, center of gravity height, and wheelbase. A tall vehicle transfers more load than a low vehicle. A short wheelbase also increases transfer.
Cornering Effects
Lateral acceleration moves load from inside wheels to outside wheels. The transfer depends on track width, center of gravity height, and lateral acceleration. A wider track reduces side load transfer. A higher center of gravity increases it. Roll stiffness distribution controls how much transfer occurs at each axle. More front roll share loads the outside front tire more.
Aero, Grip, and Safety
At speed, aero downforce can add vertical force. Lift can reduce it. The front aero balance decides where that force acts. The calculator also compares demanded drive or brake force with tire friction capacity. This helps show whether a wheel is close to its grip limit.
Practical Use
Use accurate measurements when possible. Measure wheelbase between axle centers. Measure track between tire centers. Use a realistic center of gravity height. Start with mild acceleration values. Then test stronger braking, turning, cargo, and slope cases. Treat results as estimates. Real vehicles also have suspension geometry, tire stiffness, roll centers, and road unevenness.
Model Limits
This model uses steady load transfer. It does not replace track testing or chassis simulation. It ignores tire load sensitivity details, damper timing, anti roll bar bind, and bumpy road impacts. Still, it gives a strong first estimate. It helps students, builders, and designers see how forces move through a vehicle during common driving cases and setup changes.
Use the values as guidance, then confirm critical designs with measured wheel loads.
Frequently Asked Questions
What does force in each wheel mean?
It means the vertical normal load supported by each tire. This calculator also shows optional drive or brake force and compares it with tire grip capacity.
Does the calculator include braking?
Yes. Enter a negative longitudinal acceleration for braking. The tool then shifts load forward and updates each wheel force.
How is cornering included?
Lateral acceleration moves load from inside wheels to outside wheels. Positive lateral input increases the right wheel loads in this calculator.
What is front lateral transfer share?
It is the percentage of side load transfer assigned to the front axle. It represents roll stiffness distribution in a simplified way.
Can I enter a downhill road?
Yes. Use a negative grade angle for downhill travel. Use a positive grade angle for uphill travel while facing uphill.
What does aero downforce do?
Downforce adds normal load to the tires. Use front aero balance to place more of that force on the front or rear axle.
What if my result shows wheel lift risk?
That wheel has zero or negative estimated normal force. Reduce acceleration, reduce CG height, widen track, or review the input data.
What tire friction value should I use?
Dry road tires often use higher values than wet tires. Use a conservative number when safety matters or conditions are unknown.
Can this replace corner weight scales?
No. It is an engineering estimate. Real measurements are better for racing setup, safety decisions, and final validation.
Why is center of gravity height important?
A higher center of gravity increases load transfer during braking, acceleration, and turning. Lower vehicles usually transfer less load.
Can I use pounds and feet?
Yes. Choose lb for mass and ft for length. Output can be shown in N, kN, lbf, or kgf.