tyre choice/size ?

afternoon gents , I'm soon going to be needing tyres for my nice new wheels , trials tyres as i like the style ( and have loads of usable ones from riding trials ) rear will be 400x18 , front though ? what sizes are people using ???

thanks andy

Original front was 3.50 - 19 (Dunlop K70).

I went with Avon AM6 and AM7
3.50/19 front and 4.00/18 rear