Tire Calculator Software

Tire calculator software is a very convenient tire calculation software. It can help users calculate the difference between the car's speed and the actual speed based on different tire data. The software is completely free. Users in need can download it with confidence.

Calculation method:

When the car is stationary, the distance from the center of the wheel to the contact surface between the tire and the road is called the static radius rg. Due to the radial load, the tire undergoes significant deformation, so the static radius is smaller than the free radius.

If converted based on the relationship between the number of wheel rotations and the actual wheel rolling distance, the rolling radius of the spherical wheel is rr=S/2πnw

In the formula, nw is the number of turns of the wheel, and S is the distance the wheel rolls when turning nw turns.

The rolling radius should be measured experimentally and can also be approximated.

The European Tire and Rim Technology (E.T.R.T.O) Association recommends the following formula to calculate the rolling circle:

CR=Fd

where d represents the free diameter of tires produced by E.T.R.T.O members,

F is a calculation constant, 3.05 for radial tires and 2.99 for bias tires.

The above formula conditions are the rolling circle when the maximum load, specified air pressure and vehicle speed are 60km/h, so the rolling radius is rr=Fd/2π

In the WdK criterion specified by the German Rubber Enterprises Association, the rolling circumference CR is given when the vehicle speed is 60km/h, and the rolling circumference CR’ is given at different vehicle speeds ua.

CR’= CR(1+Δua/10000) where Δua=ua-60km/h

It is generally believed that rg=rr=r (wheel radius)

Common car tire rolling radius

Tire size (m) Tire size (m) Tire size (m)

4.50-12ULT 0.264 7.50—20 0.454 175R13LT 0.290

5.00—10ULT 0.250 8.25—20 0.472 185R14LT 0.318

5.00—12ULT 0.275 8.25R20 0.462 145/70R12 0.247

5.50—13LT 0.294 9.00—20 0.493 155/80R12 0.268

6.00—14LT 0.334 9.00R20 0.484 165/70R13 0.273

6.50—14LT 0.346 10.00—20 0.509 175/70R13 0.280

6.50—15LT 0.358 10.00R20 0.500 185/60R14 0.281

6.50R15LT 0.355 11.00—20 0.522 185/70R13 0.286

6.50-16LT 0.367 11.00R20 0.512 195/60R14 0.286

6.50R16LT 0.360 12.00—20 0.541 195/75R14 0.315

7.00—15LT 0.367 12.00R20 0.531 215/70R14, 0.319

7.00—16LT 0.379 145R12LT 0.262 215/70R15 0.332

7.50—16LT 0.393 155R12LT 0.267

7.00—20 0.439 155R13LT 0.278