Al, it's not so much the air tip as it is the access to the stem because it gets pretty tight back there. For what it's worth I have mine facing the disk and not the chain in hopes that a chain/chain guard disaster won't rip out the valve stem at the same time; admittedly a small comfort should that disaster actually occur. I suspect there's probably not a right or wrong direction. Moe's right side placement would actually be a bit easier to access with the bike on its side stand.
