hi everyone, i'm new here. trying to get some advice on tire-fitting issues.

my situation is as follows: i have a 700x20 rear rim, and i'm trying to put a new tire on it. i first got a Michelin Dynamic 700x23c. which didn't look like it would fit. then i tried a Continental Ultra Sport 700x28c. however i'm still having trouble getting even the first side onto the rim.

two questions:

1.)are either (or both) those tires the right size for the rim?
2.) i noticed the tire i took off was a 27" x 1 1/4. i know its the wrong size, but it seemed to work fine before. would it be a bad idea to use a 27" tire on a 700c rim?

thanks in advance,

johnty

*edit* i notice i accidentally posted in Classic/Vintage. so i'm going to attempt to redeem myself by posting a picture of the bike:


its a 1980's Schwinn Voyageur. not sure of the exact year (if anyone knows how to find out?). its missing a lot of the original components: when i got it, the original fork was totally bonded to the stem, and i had to heart-wrenchingly saw it off.