Originally Posted by
CharlieFree
If you want flat protection I would opt for the Marathon Plus over the Greenguard. I have never had a single flat on my 25s over all sorts of terrain. Admittedly, they are not the lightest tire out there but I would rather be a minute or so slower than spend time fixing flats. I have heard the Greenguards are not as flatproof.
I don't think that one is available for 27 inch rims.