Could be a can of worms! But what width of tyre is best for climbing off road mainly grassy climbs And descents with a bit of forest road minimum. Very steep short climbs looking for good grip but somehtIng to train hard and fast on?

I have a set of Mtb cx continental tyres, I’m thinking they would be best?

If you’re training, does it matter? A big tyre will grip more and make you work harder. For racing, narrower makes grass less annoying.

actual width, or manufacturer stated width

Hmmm suppose not as its training ! 😉
If muddy is it narrower is better?

http://bikemagic.com/gear/10-of-the-best-mud-tyres-mountain-biking.html