Centre caps?
 

I have noticed that certain cars have red and blue centre caps. Is this to differentiate assymetric tires? If yes, which colour is which?

I belive that those caps you speak of are for cars that have a single lug nut which holds the wheel on, like on F1 cars. The red and blue are for left hand thread and right hand thread which assures that the rotation of the wheel will not loosen the nut.

You'll notice on these cars that the reds are on the right side usually while the blues are on the left.

Thanks for that.