I spend half my time riding over, around, through, or under chunks of re-frozen-snow-water-dirt-ice-rocks which are the size of your fist or maybe a shoebox. An unstudded 23 is going to bounce of that like a greasy racquetball. Add to that mix: dark, traffic, fogged glasses, frozen feet and I'll take a wider tire. In fact, give me the fattest thing you got.