On a four wheel drive how many inches or centimeters is one rotation unit?

On a four wheel drive how many inches or centimeters is one rotation unit or 1 rotation?

I assume you mean how far the robot moves per rotation? That depends on your wheel size. Assuming no slippage, the 4" wheels would move around 12.57", more accurately 4pi. One rotation of the wheel moves the robot the circumference of the wheel, equation of which is pi multiplied by the diameter of a circle. In the 4" example, you’d multiply 4, being the diameter, and pi.

If you’re asking how many “ticks” are in one rotation, I just don’t know. 360 seems reasonable, but that can’t be right, can it?

So 1 FULL rotation is 12.57 inches?

I am using the regular wheels which I do not know the dimensions.

Yes. If you want to be sure, take a ruler, measure the radius of your wheel, then use the formula for the circumference of a circle to find the circumference of your wheel. In your case, the radius is 2, so multiply that by 2pi to get ~12.57 inches.

95% of the questions you asked have either already been asked, or are simply google-able. Just look stuff up before posting.

PI*Wheel diameter is how far you move in one rotation. The 4" omni wheels are only nominally 4" and the actual diameter is affected by how far they sink into the foam. But 12.57 will get you close enough.

Robot turn degrees is approximately the motor degrees / (distance between the centerline of the left and right drive wheels / wheel diameter).

But now I’m curious. Does anyone know how many “ticks” are in one full rotation of the axle?

Depends what you’re using -
Two-port quadrature Encoder: 360
Old single port Encoder (or two-port with only one plugged in): 90
IME (Integrated motor Encoder) torque: 627.2
IME speed: 392
IME turbo: 261.333

Encoder info source: https://www.vexrobotics.com/276-2156.html#Other_Info
IME info source: https://www.vexrobotics.com/motors.html#Description