A tire is male, because it goes bald and it's often over-inflated.
A hot air balloon is male, because, to get it to go anywhere, you have to light a fire under it, and of course, there's the hot air part.
A subway is male, because it uses the same old lines to pick people up.
A hammer is male, because it hasn't changed much over the last 5,000 years, but it's handy to have around.