That looks like a solid touring bike! I see that most folks are recommending slicks, and I think they're right. In my own experience, I found that 32mm tires were great for riding on the road and on dirt, but started to get pretty squirrely on a loose gravel trail. I wouldn't hesitate to stick with the 32s, but there's no way I would go any smaller, and my next touring tires might be 35mm!