Hi Harry,
When I first got my CRM, it has Trailwings fitted & they were fine on-road but cr*p in the mud. When I started using it for greenlaning, I fitted some Bridgestone Gritty's (90/90-21 ED661 front/140/80-18 ED668 rear) that I picked up for £23 off ebay. They were a revelation & gave a load of confidence in all but the worst of conditions. The rear wore, way too quickly though... so I picked up another rear from ebay. This time it was a Michelin Enduro Comp 3 & this one has given exactly the same fantastic ride off-road, but has been much harder wearing. It's worked well in gravel, rock, grass, snow & mud &, together with the Gritty front tyre, is still working well after 6 hard days riding with around 250-300 miles/day, split about 175 miles on-road & 75 miles off-road. Road sections including motorways done at speeds up to 80mph have only just started to round off the main blocks. I'd definitely be happy with this combination again.
HTH,