I was getting worried that you were a complete idiot .

Phil,
Try www.mytyres.co.uk . I would find out what the OE tyre was with these wheels, as some cars need a certain tyre-wall rigidity to give them the best handling, so certain tyres will be completely unsuited (even though they are the correct size). For example, the Lotus should only really run Goodyear GSDs which are specific to the Esprit and no other car....