Nobody here rides tires skinnier than 28s, and only one of us ever rides them, and that’s only occasionally. Mark, our fastest guy, rides 32-33mm tires on his fast road bike on the fast club rides, and if he’s not slowed by them (and he’s not), then you won’t be, either. There’s no reason to ride a 25mm or skinnier tire, ever.
Over time, if you’re in the same Phylum as us, you’ll find yourself valuing strength, reliability, and cush over max zippiness. When the task at hand is a ten-mile commute, a 300-mile tour, a trip downtown shopping, or a solo ride or a ride with friends who don’t see you as the enemy, then go bigger and heavier with your tires. A “starting” size, if you’re in transition between fake racer and real worlder, is about 38mm. You can do a lot with that size. Now, “38mm” in real actual widths means anything from 34.5mm to 38mm—because labels are always fatter than the actual. But that’s a useful tire. You can run it hard or soft. Or start with it hard, then let it leak as it will anyway over time, and when it starts to get squishy in 4 months, pump it up again.
The general rule, in any case, is to ride one notch fatter than your psychological comfort level. When that catches up and you need new tires, go one fatter, still.
Bike tires are incredibly expensive these days. More than cheap car tires. But good tires play a bigger role in safety, too, so don’t ride bad ones or worn-out ones. The stoutest tires in the land, and among the most expensive, are Schwalbes. Worth it.