rajman

I've only bought tires as singles. It's never been a problem.

Because I'm riding relatively upright, most of the weight is on the rear - especially if I'm hauling books, groceries, beer or locks (which is pretty much 100% of the time).

In my experience, putting a skinny tire on the rear has had a marked effect on rolling resistance, with no noticable effect on handling/braking speed/getting stuck in streetcar tracks.

The exeption is the winter bike - where I have a snow stud b/c when it's fully inflated - the studs do not contact the road = low resistance, when I let out the air, studs make a lot of contact. This way if I'm riding on black ice, i'll put the rear studs out (one of the few instances where rear braking is a good idea) if it's just snow or small ice patches, pump it to the max - and it's like I'm riding a knobby.

Bizikleto

What tires do you use?
Commuter 1: Schwalbe Big Apple
Commuter 2: Schwalbe Kojak

How wide are they?
Commuter 1: 2.0",48 mm
Commuter 2: 1.35", 35 mm

What is your wheel size?
Commuter 1: 700c, 28"
Commuter 2: 26"

How long is your commute?
12 mi, 20 km RT

What is the general average terrain? Ashphalt, dusty road, pebbles, bumps?
Asphalt and some hard packed trail

General weather conditions for your commute? 30% heavy rain...snow...sunshine...etc...
Winter: cold, dry air with wintry showers. 2 in (5 cm) snow about 5 scattered days in the whole season
Summer: warm, sometimes hot, with dry air and occasional convective storms.
Spring and Autumn: chilly mornings, warm afternoons with drizzles and some heavy rain.

nashcommguy

#1 commuter-Nishiki steelframe roadie, sandblasted and powder-coated. Nuteck airless, 38mm(rated @ 110 psi), 700c, 30 mi rt, rural asphalt, conditions vary from rain, heavy rain, very cold(15F), very hot(95-100F w/80% humidity), snow, etc.

#2 commuter-Fuji steelframe roadie, sb + pc, too. Kenda Kwest 28mm @ 100 psi(w/Mr. Tuffys), 700c.

#3 commuter-Fuji Discovery MTB. Kenda 1.75X 26(w/Mr. Tuffys)

littlewaywelt

What tires do you use?
Performance Forte City (just switched after five years of riding mtb tires).

How wide are they?
1.5

What is your wheel size?
26

How long is your commute?
4 miles rt

What is the general average terrain? Ashphalt, dusty road, pebbles, bumps?
decent streets

General weather conditions for your commute? 30% heavy rain...snow...sunshine...etc...
95% dry

MCODave

What tires do you use?
Vredesten Fortezza SE

How wide are they?
23mm

What is your wheel size?
700c

How long is your commute?
32 miles r/t

What is the general average terrain?
Smooth to pockmarked roads, no hills

General weather conditions for your commute?
Warm humid mornings, hot humid afternoons with occasional downpours (central FL)

If I had two tires of different sizes I think I would put the wider one on back as is standard on virtually all motorcycles. Not saying the other way around doesn't work, just haven't tried it.

peter418

What tires do you use?
armadillo elite crossraods

How wide are they?
1.95mm?

What is your wheel size?
26"

How long is your commute?
10 or 20 miles r/t

What is the general average terrain?
concrete

General weather conditions for your commute?
Warm humid mornings, hot humid afternoons with occasional humid downpours (south LA)

peter418

1.95"s?? forgot

Psimet2001 

What tires do you use?
Michelin Pro2Race

How wide are they?
25 in front - 23 in rear - used to both be 25, but I ended up with clearance issues in the rear

What is your wheel size?
700C

How long is your commute?
50 Miles RT

What is the general average terrain? Ashphalt, dusty road, pebbles, bumps?
MUP(80% of route) - Paved but some un-paved sections. Surface streets in cities along route.

General weather conditions for your commute? 30% heavy rain...snow...sunshine...etc...
Mostly dry or wet from rain the night before. Can get dicey in un-paved MUP sections.

DogBoy

Mich. Transworld City
26x1.95/700-38
5-8 miles 1 way depending on route
City roads/potholes and county hwy/potholes
General weather conditions? WIND!

mrsmiff

What tires do you use?
Conti Sprinter Gatorskin tubs, Tufo S33 tubs, one random tub that may or may not be a conti.

How wide are they?
From 19 to 25. Gatorskins are 25s, and will be replacing all my other random tires over time.

What is your wheel size?
700C

How long is your commute?
10 miles rt + errands

What is the general average terrain? Ashphalt, dusty road, pebbles, bumps?
Streets, sometimes MUP

General weather conditions for your commute? 30% heavy rain...snow...sunshine...etc...
Typical norcal weather, dry except for rainy season.

I've standardized on all my 700c bikes having tubulars. I get significantly more flat free miles, and seem to have to pump them up a lot less. I've had one flat a year on them so far, and it's almost always my fault for either riding through glass or skidding through the carcass.

tarwheel 

What tires do you use? - Michelin Open Pro, M. Pro Race2
How wide are they? - 23-25 (Michelins run wider than most brands, so 23s are like 25s, and 25s are like 28s)
What is your wheel size? - 700c
How long is your commute? - 20-25 miles (RT)
What is the general average terrain? - mostly smooth paved roads with plenty of hills
General weather conditions for your commute? Fairweather (don't ride in rain unless caught)

mjoemoon

What tires do you use?
Michelin Country Rock

How wide are they?
1.75

What is your wheel size?
26

How long is your commute?
7 miles rt

What is the general average terrain? Ashphalt, dusty road, pebbles, bumps?
Pavement, loose gravel on pavement this time of year (yikes!), a short stretch of packed dirt.

General weather conditions for your commute? I'll ride in all but the worst weather. Not snow and ice though =)

I have a friend who owns a bike shop so I've been able to try a few different tires over the last 2 years. These are my favs by far. Very smooth rolling for a mtb tire and great traction on everything I normally ride through. Also, I live in a fairly bike-unfriendly ( possibly even bike-hostile ) city and have been forced to ride over some pretty nasty stuff to avoid traffic. These tires seem almost indestructible.

Podolak

What tire do you use? - Borough CX Armadillo Elite
How wide are they? - 32
What is your wheel size? - 700c
How long is your commute? - 30mile RT
What is the terrain? Asphalt, dust road, pebbles, bumpy/s? - Asphalt
General Weather Conditions for your commute? All weather conditions; snow, rain etc.

sean000

What tire you use?
Continental Top Touring 2000 (discontinued, but they still offer similar tires).
I ride the 700x37s between 50psi and 75psi depending on whether I'm going for speed or comfort.

How wide they are?
37mm

What is you'r wheel ssize?
700c

How longs your' commute?
8 to 10 miles round trip (depending on route and whether I stop for groceries). I often extend the evening commute another five or ten miles for fun and exercise.

What is the gen.l averege terrainne? Asphault, dust road, pebbles, bumpy/s?
Smooth roads, bumpy roads, and a gravel/dirt multi-use path that can be bumpy in places.

General Weather Conditions for your' commute? 30% heavy rain...snow...sunshine...etc...snow
Mostly sunny and clear in the Summer... rarely hotter than 80 degrees F. Mostly cloudy with frequent light to medium rain in the Winter. Winter temperatures rarely dip below 35 degrees, and heavy rain is infrequent. Snow is rare. Damp and muddy conditions are the norm. I use fenders. Spring and Fall you can get all of the above.

GreenPremier

Gatorskins
25mm
700c
9 miles round trip
Road/bike path
It's Iowa, so any weather goes. Hot humid in the summer, cold/windy in the winter.

xylophonecks

What tires do you use?
Continental Gatorskins

How wide are they?
23

What is your wheel size?
700c

How long is your commute?
Now it's about 12 miles round trip, but was considerably longer until somewhat recently.

What is the general average terrain?
I've worked my route to take the smoothest roads possible, but there are still a few sections of bumps/potholes/cobbles

General weather conditions for your commute?
generally fair, and fairly windy.

knobster

I use 2 bikes for my current commute.

What tire you use? Bike 1: Ritchey Tom Slick, Bike 2: Specialized Cross Road Armadillo
How wide they are? Bike 1: 26x1.4, Bike 2: 700x38
What is your wheel size? See above.
How longs your' commute? 10 miles. It's 2.5 miles one way, but I go home for lunch.
What is the gen.l averege terrainne? Asphault, dust road, pebbles, bumpy/s? Very nice pavement with bike lanes. To work I can almost coast the entire way.
General Weather Conditions for your' commute? I live in Oregon. 100% rain.

ItsJustMe

What tire you use?
I rode the cheap Kenda 38s that came with the bike for about 3600 miles. In the winter I've been riding Nokian Hakka 35s. When the Kendas wore through, I put on some Bontrager Race Lites 32s. They were OK but I don't think I got the miles out of them I should have. Right now I'm running Conti Top Touring 2000 32s; a friend gave them to me; they were on his bike when he bought it but he likes slicks so I got them with only 30 miles on them.

I don't have to put up with flats much. I don't take any special measures against them, and I only flat once a year or so unless I do something stupid.

My commute is 21 miles round trip. 8 of that is gravel/clay/sand mix which can be muddy if it's wet, but is pretty good most of the time. The rest is pavement with no potholes, though there are a few rough spots (a bad bridge).

The weather is mostly dry in the summer, though I ride regardless of conditions. In the winter I'm on snow and ice some of the time, on the Nokians.

In general, the rougher the roads you ride, the wider a tire you want. 32s are a good compromise; they're reasonably fast but still have plenty of cushion. 28s are still not bad for mildly rough road.

If you have to deal with pointy things (glass, thorns, etc) then look into tires with flat resistant layers like kevlar or more serious protection like Marathon Plus, or even put in a tire liner like Mr. Tuffy.

Tread in general is not useful on pavement. It is not necessary for wet roads unless you can get up to about 80 MPH on your bike. Tread helps on loose surfaces.

jefferee

What tire you use?
Winter: Schwalbe Snow Studs
Summer: worn knobbies... don't know the brand, just came with the bike.

How wide they are?
Winter: 1.90"
Summer: 2.35"?

What is you'r wheel ssize?
26"

How longs your' commute?
10.5 km / 6.5 mi

What is the gen.l averege terrainne? Asphault, dust road, pebbles, bumpy/s?
Winter: Generally bare asphalt/potholes, with occasional snow cover and constant risk of black ice
Summer: Asphalt/potholes, some MUP gravel, occasional canine leavings...

General Weather Conditions for your' commute? 30% heavy rain...snow...sunshine...etc...snow
Winter: Anywhere from -20 C/0F to +10 C/50 F, frequent snow, occasional rain
Summer: Mostly sunny, fairly frequent weather systems bringing rain/thunderstorms