Bicycle Mechanics - Replacing thin tires.

I recently got a road bike for the first time -- many years of large or medium
tired hybrids or mountain bikes. Here's a question about these thin (25) tires.

Replacing a tube, I had a devil of a time getting the tire off the rim, and
a considerably worse time getting it back on. I have tire levers, but
on the first attempt to remove the tire, I snapped two of them trying
to get the tire off the rim. This was probably because I have presta
valves (also a first for me) and didn't realize you need to unscrew the
nut on the valve before removing the tube. I still don't quite see the
physics of this, but once I got that, removing the tire wasn't too
bad, and fortunately I had some extra levers. Still, it wasn't nearly
as easy as removing thicker tires had been on hybrid bikes. Is this to
be expected? (Also, I frayed the very inner edge of the tire a bit trying
to work the levers beneath it to prise it up. This just doesn't sound
right.)

But putting the tire back on! What a nightmare! Everyone says don't
use levers, because obviously pinching the tube would be a bad thing.
But unless there is some trick I haven't figured out, there was simply
no way to get the tire back on without the levers. I'm not the strongest
guy in the world, but once I had the six-eight inches of the tire left
to snap into the rim, it was short-cutting the rim in a hard, straight
line that I could not budge with my fingers. It took me a good ten
minutes to inch the tire back into the rim by (very carefully) using
the levers.

There's got to be some trick to this, right?

(Tires are 700x25.)

Man do I feel like a newb asking for help with a flat tire. Fortunately,
I was doing this repair at home, in the relative privacy of my own
driveway, rather than along the road, looking like an idiot. So I figure
I'll get your advice here rather than look like an idiot next time...

Couple of things.

First, as a general rule, I think that you will find road tires to be a little more difficult to mount than hybred tires. Some tire and rim combinations, however, are MUCH more difficult to work with than others. There are a couple of tricks that make the whole process quite a bit easier.

1. When removing the tire from the rim, the first thing to do is to pinch the beads together all of the way around. The rim has a low spot in its centerline. You want both beads in that low spot to give you the slack that you need to pry the opposite side off of the rim.
2. The next thing that I do is to stand the rim up on the ground in front of me. Then I put my hands on the tire at the 9:00 and 3:00 positions and push down toward the ground as hard as I can. Most of the time that gives me enough slack so that I can take the tire off without using tire levers.

3. To reinstall, I blow up a presta tube with my mouth and install the tube in the tire while it is still completely off of the rim. Life is lots easier if the inner tube isn't oversize for the tire. A little bit undersize is OK.
4. Reinstalling is the opposite of taking the tire off. Make sure the beads are near the centerline of the rim and use the 9:00 and 3:00 trick to give yourself the maximum amount of slack.
5. If you have to resort to using a tire lever to pry the last few inches of bead onto the rim, be sure to take the time to push the bead away from the rim and peek in to be sure the innertube hasn't been pinched.
6. Pump the tire up to about 30psi. Check both beads all of the way around to be sure they are seating evenly and reinflate the tire the rest of the way.

Retro's procedure is THE way to do it.

I would add step 0.5) After letting all the air out of the tire, push the stem down into the tire, so the beads can get closer to the center, giving you a little more slack.

And to elaborate on steps 3 and 4 a little, the idea is to put enough air into the tube to give it some shape so it will stay in the casing while you're slipping the first bead onto the rim. Then you push the tube over the edge of the rim, so it and the first bead are in place. (The first bead and tube are now up in the casing, seated in the rim. The tube is not laying flat, where it will get caught under a bead.) Now, start working the final bead onto the rim. I put the stem at 6:00, and start putting the second bead in there. Push the stem down into the tire so that it allows both beads to seat and center as much as possible. Then work your way up both sides simultaneously. I generally have to release some air a couple of times as I go as the process will force more pressure into the unseated area. Just keep enough in the tube so that it isn't laying flat in the rim. By the time you're working the last couple inches on, the bead pulled tight against the outside of the rim, and you have let pretty much all the air out of the tube. If it's particularly tight, it sometimes helps to repeat the steps of pushing the stem in and centering the beads to get a little more slack to push the last little bit on.

Once you've done it a time or two, it takes lots less time to do than it did to read the procedure. ;)

There are a couple of tricks that make the whole process quite a bit easier.

Thanks for the tips, Retro. I expect this is exactly what I needed to know.

And sorry for the double post. It froze the first time, and I checked the forum
to see if it had shown up and it hadn't, so I tried again, fixing the title as
I did so. Ah well. A newb in all regards, I guess.