Just thought I'd give you guys the benefit of my mistake, my car has 14" wheels so naturally I though I could cover them with 14" pizza trays.
I couldn't find 14" aluminium pizza trays in any of the local shops, but I found a trade catering supplier near my work, who agreed to supply me with just four trays. I picked them up today only to find that they are in fact 13.5" in diameter and the hubcaps on my wheels I was going to attach them to are 15 3/4" in diameter!
I'm now debating whether I should grab a cheap set of hubcaps from the scrappies and attach the trays and paint the whole lot black so you can't see the hubcap behind them.