Tire weight - makes a diff for me. besides the 'feel' of the tire, poppin up small rises, startups and any accels just go easier with a lighter tire.
Another effect of a lighter tire is generally a more supple casing. More supple from lighter weight, higher thread count, means less bouncing over road irregularities.
SOme times you can make a real find.
My first week on my new commuter/shopper/errand bike (replaced a very tired and now broken Fisher Tassajara convert)- '06 Spec Roubaix - was 2 days on the 23s I had on the Ritchey OCR Aero Pros I had on there... Fast, nice, but a bit too sporty once I got the rack and bags on it.
I had ordered a pr of Avenir Discovery 28c tires from Amazon, $18 ea, shipped free with 'prime', just to see what a wider tire on this bike might feel like.
So when they came in, I put them on a PerfBike Titan wheelset I had hangin around and slapped them onto the Roubaix. Rode the next 5 days on them, commute and shop. Very Nice! After experimenting with pressure, I ended up airing them at 70 lbs frnt and 75 rear, for a great compromise of feel and comfort. I'm 160 lbs. But even for much bigger riders I think these would ride very nice in the 80-85 lb range.
I weighed the Avenire Discovery at 296g - 20g lighter than the 'spec'. I believe this is the Kenda K176 tire with a 60tpi casing.
A great deal at $18 each - nice tire!
went back to amazon, today, to buy a few more - price went up to $23 ea in the 2 wks since I bought my first pr. Still a nice tire at a good price, but maybe I'll wait until they drop price back to the teens...