ok heres my deal. one of my front tires loses psi slowly, when sitting i add every week. the back tire has a nail in it (looks like a 8 penny nail. i hear about tire slime and was wandering if i should add it all around or fix the problems first. thanx. Ryan

 

Pull out the nail and put in a plug. that should solve your psi loss. if that don't work try the slime(which i don't think will work to good) but it's totally up to you.

 

This is just my opinion, but I refuse to put anything in my tires except air. If there is a leak, find it in a tub of water (look for the bubbles), then fix it. Slime and fix-a-flat suck to have in the tire when a dismount is needed to fix a leak right after they fail.
Plugs work great for punctures - I have plugged tires that have been running for years. I never leave home without a plug kit.