Joe,

I recommend that you measure the width of your rims, and then go to
Sheldon Brown's website to see what range of tire widths will fit
properly.

http://www.sheldonbrown.com/tire_sizing.html#width

IIRC the number in the tire size (like your 35mm) is really the tire
height, not the width, although the width is just about the same as the
height.

The effort it takes to propel a bike is dependent on the tire rolling
resistance. To a first approximation, rolling resistance is dependent on
the tire pressure and width. Generally speaking the narrower the tire the
higher the pressure and the lower the rolling resistance. Depending on
your rim dimensions you may be able to use tires as narrow as 25mm. For my
road work I use 700x23 and 700x20's, on narrow rims.

To further lower the effort required to propel the bike you can get light
weight tires and tubes. This will lower the rotating mass and make it
easier to accelerate the bike. The lower limit for clincher type tires is
about 200 grams, some run up to 400 grams.

Tires narrower than 25 mm are sometimes difficult to mount, and require
pressures of 90 to 120 psi. You may need a new pump. The narrower the
tire, the higher the pressure, and the rougher the ride. I do not find my
20 and 23mm tires objectionable from a ride point of view, but my roads
are not bumpy.

As for tread, at the risk of being flamed, it has been my experience that
it really doesn't matter that much for road work. Just make sure that the
tread is reasonably smooth, and does not have knobs. Buy a "road tire" and
you should be OK.

HTH,
Ernie

Joe Samangitak wrote:

I have 700 x 35 tires on my hybrid bike, and I've recently learned
that I can change the 35 (width?) to a different size, ie. 32, 28 etc.
Question is, do I want to? I ride exclusively on pavement in a city,
so I'd like to maximize tire efficiency for this type of driving.

- First of all, will it work to put different width tires on my
hybrid/city bike, or is there an issue with narrower widths coming off
the rim, etc.?

- Secondly, is there an advantage to using a different tire size if I
can, or should I assume the original 700 x 35 tire size was already
designed ideally for city driving?

- Lastly, I read expert testimonials that said slick tires are best
for pavement riding, cornering, wet driving, traction and have less
rolling resistance, basically because more rubber contacts the road. I
was looking to buy the Michelin Transworld City, but its not a pure
bald slick, it has fairly deep recesses, presumably to siphon off
water (which I read isn't necessary for bike tires, and that this
system doesn't work better than slicks). So my question is, would I be
better off driving in my city with a pure bald slick, such as the
Avocet Road 20, instead of the Michelin Transworld City? Or is it even
better to use DIFFERENT TIRES for the front and back? Any commonly
known disadvantages to going with pure bald untreaded slicks on
pavement, such as premature tire wear, as compared against tires with
a tread?