Originally Posted by
Darth Lefty
I'm trying to imagine how a Marathon Plus in 25mm has room for any air inside
That made me laugh!
OP, I would suggest you also consider a pair of liners. I have had very good success with Mr Tuffy's, there are other brands as well. For less than the cost of a pair of tires, you get liners that can be reused in unlimited sets of tires. Many people have reported problems with the liners causing flats by the squared-off ends rubbing, but it has never been a problem for me.