I've got these (Continental Cyclo X Speed Tyre) at the moment. So far I've only ridden them on the road though, no idea what they're like off tarmac yet. I've got the 32s, they are massive, like the same width as my 26 x 1.75" mtb tyres, you'll need big clearances. No idea what you can get on the high street, mine were from CRC, and bought maninly because they were cheap and not too nobbly (higly technical I know).
I've got these (Continental Cyclo X Speed Tyre) at the moment. So far I've only ridden them on the road though, no idea what they're like off tarmac yet. I've got the 32s, they are massive, like the same width as my 26 x 1.75" mtb tyres, you'll need big clearances. No idea what you can get on the high street, mine were from CRC, and bought maninly because they were cheap and not too nobbly (higly technical I know).