# Calculating tire sinkage and deformation

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As we all know, car tires sink into surface because the pressure which they produce deforms the surface a bit. Usually this amount is so small that we can't notice it. However, it does affect car's handling as this sinkage increases rolling resistance force. This is the first step which I want to calculate.

Secondly, the wheels deform by theirselves. They don't result in flat deformed tires, because they're elastic enaugh to regain their shape.

I want to calculate the sinkage depth and deformation distance as shown in the image.

[attachment=31713:problem1.png]

I need to find out 2 numbers(in cm):

• A - B
• C

So - what are the required inputs(e.g. load, tire wall radius) and what are the equations?

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>> As we all know, car tires sink into surface because the pressure which they produce deforms the surface a bit.

first time i ever heard that one, and i a have a 9 second car in my driveway.

if the pavement was asphalt, and the temperature was high, some slight deformation might occur, but not enough to worry about.

rolling resistance of the tire is the only real issue. and that's a function of tire pressure and compound stiffness. the result of which determines the values of A and (B-C). and C is zero.

Edited by Norman Barrows

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False. C can reach between 0.01 - 0.1 cm on asphalt(depending on conditions). On surfaces like gravel or mud, however, it can reach big numbers, even above 1 cm.

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Hm... Is there a good reason to understand the physics behind/simulate this, or would it be easier to look up real-world data and just use that to approximate it?

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I am not sure about it.

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