If you're going to do 19's, reference the chart for whichever width you plan on getting:
http://www.ft86club.com/forums/showthread.php?t=7535
Stock wheels are 7" +48, and there are numerous safe fitments on the chart to choose from.
I use this site to calculate wheel movement changes:
http://www.gtsparkplugs.com/WheelOffsetCalc.html
Though I personally wouldn't install 19's on it. Prefer 17 on a car this small, as I feel anything larger (18 is negotiable) overpowers it and makes the wheels the focal point when rather they should compliment the car.