Depends on the roads and the clutz factor. I can, if alert, ride tubulars on rough stuff. I can also kill 25s on relatively benign roads if I behave like a dofus. Conti gatorskin 28s should probably take most people through most stuff and be adequately fast. Lots of other choices, for sure. Don't be scared of skinny, just learn to be alert. Of course, tempered by weight. Heavy people need fatter tires. Light people can ride rather skinny at fairly low pressure.