void FixedUpdate()
{
    Vector3 euler = rb.rotation.eulerAngles;

    float targetYRotation = euler.y + (inputDirection.x * Time.fixedDeltaTime * speedMult * rotaRatio);

    float maxTilt = 20f;
    float targetZTilt = Mathf.Clamp(inputDirection.x * -maxTilt, -maxTilt, maxTilt);

	if (inputDirection.x == 0f)
	{
    	targetZTilt = 0f;
		wheelingDuration = 0f;
	}
	else
	{
		wheelingDuration += Time.DeltaTime;
	}

    float smoothedZTilt = Mathf.LerpAngle(euler.z, targetZTilt, wheelingDuration / duration);

    Quaternion newRotation = Quaternion.Euler(0f, targetYRotation, smoothedZTilt);
    rb.MoveRotation(newRotation);
}