Originally Posted by scottfsmith

I have been running 30mm for several years now .. first some Specialized S-Works Turbo and now GP5000 S TR. Its not worth going up 2mm if your old tires are not worn out, but when my old 28s wore out a few years ago I got 30s and definitely appreciated the touch of extra comfort and grip.

When the Turbos wore out I thought about getting 32s but decided to just stick with 30s.

Note that todays 30 is the same as a 28 from several years ago - tire companies shifted their sizing since the average rim got wider which fattened how tires sit. If you are on fresh 28s those are like 25s from the past. Another reason to bump up the size a bit perhaps.