I've just spent about an hour replacing my worn Maxxis Overdrive tyres with 2 x new brand spanking Schwalbe Marathon Plus Tyres.
I was warned that these tyres can be difficult to fit but managed to get them on okay.
The problem is that these tyres have quite a 'definate' beading and the trick seems to be to get one side of the tyre over the rim first then. On the other side, keep repeatedly slowly turning the wheel and feeding the beaded edge of the tyre onto the rim. During the procedure, I did initially inflate the innner tube a bit but then let a little air out. Eventually the tyre just pops onto the rim with perhaps two or three levers. I then made a final check of the tyre to make sure it was equally seated on the rim on both sides.<moderator edit: have copied this topic to "Too Good to lose" as it contains some good hints and tips, especially the link to this video: http://www.youtube.com/watch?v=-XUFVrl0UT4 by Spa Cycles>