Most of the people that I spotted with visitations on the Claerwen reservoir track seemed to be on relatively wide tyres. I could well be wrong but I decided that this was probably because they were hammering along whereas I felt the need to pick my line fairly carefully on my 28mm Conti 4 seasons.
I think there's some sense in that! I rode that section twice this year, both visitation free, very different rides:
- April, recce on a tour with 25mm tyres. Rode VERY steadily, picking my way between the biggest stuff (and had to take my shoes/socks off for the ford)
- TINAT, on 35mm slick-ish tyres. Rode a lot faster, just keeping an eye out for really massive rocks. Actually enjoyed the scenery
In generally, bigger tyres will be more resistant, if only from pinch flats. [Many variable apply, don't sue me ... ]