The current tyres are Schwalbe Lugano 700 23c and I use the bike for 20-30 mile recreational rides on country roads, many of them in a poor state of repair. I'd like to put something a little heavier on, so that I am not constantly forced out into the middle of the road by the more minor potholes and botched road repairs. I weigh 10 stone. What sort of tyre size should I look for, and can you recommend a specific tyre?