I guess I made more of a tire endorsement than a real reply so here
goes:
Quoted message said:On impulse I bought a cheapo tire in my last Nashbar order. I'm glad I did
because I needed it unexpectedly. Now I'm wondering, though, how to shop
more intelligently.
Hey, grabbing cheap tires on sale at Nashbar is very intelligent!
Nothing wrong with having a few spares hanging in the garage you got
for cheap.
Quoted message said:I ride an old steel bike with 27" wheels, which narrows things down to begin
with. Even so there are a bewildering array of options--kevlar vs. wire
beads, water-shedding treads, kevlar belts, etc.
Treads are insignificant except when they're too aggressive for road
tires, and cause "squirm" and thus energy loss through friction. Tread
is mostly decorative on road tires. Plenty of posts to search about
this.
Quoted message said:The newer tire is noisier than the one it replaced, and if noise corelates
to friction that can't be good. Or can it?
Tire noise usually means excessive squirm and friction for sure.
Quoted message said:The tire it replaced was an IRC HP 90, which had a raised ridge about 1/4 of
an inch wide in the middle of the tread. Is this useful? Should I just stick
with that?
Ugh. Raised ridge tires are to be avoided in my opinion. it's just bad
design. They also make cornering a bit wierd feeling.
Quoted message said:The IRC is a heavy tire (about half a kg). Usually I don't care about weight
(if I did I'd get a lighter bike), but tires spin and affect gyroscopic and
centrifugal forces so perhaps it's worth paying attention to. Does it
matter?
Tire weight and sidewall suppleness make a huge impact on feel,
cornering, and efficiency. A few grams here or there matter little to a
recreational cyclist, but a 150g difference is pretty palpable when
accelerating.
Quoted message said:I ride medium and longer recreational rides, not in the city but on roads of
varying conditions.
Quoted message said:I'd be grateful for explanations and advice that will help me make the right
choices. What do I need to know?
That there is a lot of tire hype. Get something in a width that's
appropriate. 1 1/8" for basic fairly fast riding, 1 1/4" if you want a
little more comfort on rougher roads.
I'm on the fence about kevlar/aramid belting but tires I've ridden with
it certainly *seem* to get fewer flats.
I still recommend those Vittorias.