What is the hydroplane speed formula Vhp in terms of tire pressure?

What is the hydroplane speed formula Vhp in terms of tire pressure?

• A. Vhp = 9 × tire pressure
• B. Vhp = 9 + sqrt(tire pressure)
• C. Vhp = 9 sqrt(tire pressure)
• D. Vhp = 9 ÷ sqrt(tire pressure)

Answer: (C)

Hydroplane onset is governed by a non-linear interaction between tire load and the water being pumped out from under the tire. Empirically, the speed at which hydroplaning begins grows with the square root of the tire pressure, meaning Vhp is proportional to sqrt(tire pressure). The constant 9 serves as a unit-scaling factor to fit the measurement system used in this context. Thus, the form that matches this relationship is 9 times the square root of tire pressure. The other options would imply a linear, additive, or inverse-sqrt relationship, which doesn’t reflect how the water film and load interact to raise the threshold speed.

Hydroplane onset is governed by a non-linear interaction between tire load and the water being pumped out from under the tire. Empirically, the speed at which hydroplaning begins grows with the square root of the tire pressure, meaning Vhp is proportional to sqrt(tire pressure). The constant 9 serves as a unit-scaling factor to fit the measurement system used in this context.

Thus, the form that matches this relationship is 9 times the square root of tire pressure. The other options would imply a linear, additive, or inverse-sqrt relationship, which doesn’t reflect how the water film and load interact to raise the threshold speed.