Extend and override in php

class Vehicle{
var $color;
var $wheels;
var $doors;
function upload_image($file)
{
 echo 'image here';
}
function is_good_for_rain()
{
return true;
}
}
class Car extends Vehicle
{
 var $wheels=4;
 var $doors=4;
 var $convertible=false;
function is_good_for_rain()
{
 return !$this->convertible;
}
}
class Motorcycle extends Vehicle{
Var $wheels=2;
var $doors=0;
function is_good_for_rain()
{
 return false;
}
}