Both this and the Motorcycle are not doing a class method correctly. If you want Automobile to override a vehicle, you'll do

```ruby
class Vehicle
  def self.tires
    2
  end
end

class Automobile
  def self.tires
    4
  end
end
```

with this, you could

```ruby
class Motorcyle < Vehicle
end

Motorcyle.wheels
=> 4
```