Radio Shack iron (25 watt) tip question

[bazz]

Well it's been awhile for me to have to replace my tip, but the time has come. Now, there were replacement tip packs I saw in RadioShack. One was a single basic copy of the one already in my soldering iron (for like $6!). The other was a pack of 3 copper looking ones, which says they are compatible with the R-Shack 25,35,and 45 watt irons. When I tried to put these on, they don't fit at all. Has anyone had experience with these? I believe they should fit.