Narrow 20 inch tyres

[adyl]

Hi, I'm using 20 inch wheels for a battery-powered electric car race (it's called Greenpower). So far we have used 1.75inch wide 20 inch Schwalbe Marathon tyres, but I wondered whether anyone has come across a more narrow 20 inch tyre, about 1 inch wide or narrower?

Cheers,

Adyl