America tyre on speedmaster?

Hi
Read somewhere on tinterweb about a speedmaster owner who had his bike in for new tyres
When he got it back was really impressed by the improved handling
It wasn't until a few weeks later that he realised an oversized America tyre had been fitted to the front
Can't find it anymore to see what make tyre it was But I know he decided to stick with it cos he was that impressed
Anyone heard of this before and what do you think