what does 700cx28 mean?
 

on a 700c x 28, would it be possible for me to put a 700c x 25 road tires on my sirrus?

My road bike came with 700x26 on it and the bike shop replaced with 700x23 so apparently yes it'll work.

The specs for your bike shows: RIMS Alex DA-16, 700c, alloy double wall, machined sidewalls

Norco produced their CRD-3 road bike with Alex DA-16 rims and 700 x 23 tires last year.

A simple yes is in order

700 refers to the theoretical rolling diameter of the tire in millimeters.
28 refers to the theoretical mounted and inflated width of the tire in millimeters.
c is supposed to be a measure of rim width as in a, b, c, d like in shoes, but in real life it has a stronger relationship to the rim diameter.

All of those measurements (except bead diameter) have a liberal amount of wiggle room. For example you can easily eyeball the differrence in width of many 700c rims. You can make minor changes in tire width, but I'd never try to use a tire that was narrower than the rim.

I'll second that "yes"

My Sirrus took 700c x 23 without complaint.

did you notice any difference on your sirrus when you put the 700 x 23 on the bike? did it make the ride rougher or faster? what kind of 700 x 23 tires did you have on there?

Rougher and faster. :)

Not sure which ones to be honest..... armadillos again?

humm.. in theory it should go faster and for sure rougher. i'm currently riding the armadillos nimbus EX on my rockhopper... i would have to say.. at 1.5" wide... it made my rockhopper faster but more bumpier. kinda makes me wondering if at all it has to do with armadillos. if it is.. then i might steer away from it.. cuz i don't want too rough of a ride.

You're only talking about 2mm difference in width, that's not very much, so I wouldn't expect a hugh change in ride quality just from that. Much bigger differences will result from using more air pressure and from the construction of the tires.

Armadillos are nearly bullet proof, but their stiff sidewalls are a detriment to both rolling resistance and comfort. They're heavy too. I have them on a couple of my bikes, but I use them only selectively.

i saw some 700 x 23 from Continental and they had pretty good tire threading too. can't remember what it was. but those look nice too. perhaps i should go back to REI to get the model name.

I run Continental GP3000 in 700Cx23. They roll really nice and handle most weather conditions well. They also seem pretty flat resistant... not as good as a true heavy-duty commuter tyre but pretty good for a racing tyre. The only downside is that they're pricey at around $45 each.

aaaa-ha! found it.. these were the continental tires i saw at REI. Continental Ultra Gatorskin

these looks and felt pretty good when i was in the store. the tires was very smooth. plus with kevlar, it almost looks flat proof. plus it's $33 which isn't that bad. have you ever experience with these?

Nope. Not personally but I have ridden with people who use them and well... They were getting flats when I wasn't. However, I think the majority of the flats were due to a bad batch of tubes but at least one was genuine. They're probably still good tyres but I wouldn't count on them being totally impervious to flats.

humm.. ic. since there were a thread on here that says specialize makes crappy tires.. i'm kinda worried about my replacement tires for later on. at first i was just going with specialized tires.. but now that thread has got me looking elsewhere. well, at least i still have time to do some more searching.. it's gonna be a while before i need to replace my sirrus tires.