i have the stock 15 inch rims and 195/65/15 tires. i really dont wanna go bigger than that wheel wise. i was thinking about 225/50/15s and i used the tire size calc. it says that the 225/50/15s will be 1.1 inches smaller than my stockers. is it enough that my computer can still adjust?????
 
When I bought my car, it was on 15's with 60 tires on it and the speedo was about 5 mph off.
I may not be the sharpest crayon in the box, but at least I'm a pretty color
 
the computer cant compensate for tires size differences.
if you go with a 225/60 15  your speedo will read 60 mph but your actual speed will be 61.6 mph 
225/50 15's will be 60 mph on the speedo when your actually moving 57.3 mph
http://www.wildweasel.ca/j-body/HowTo/tirecalc.asp

The one, the only, ME. 
 
 
I just replaced some BFG 225/60r15's with my new 18's and I never had a problem running the 60 series tires.  If the speedo was off by 1.6 mph at 60 I never knew it and the police never seemed to mind with all the radar traps that I went thru and never got nailed for doing 1.6 mph over the speed limit.  They fit,  They ride nice,  And 1.6 mph
isn't going to make a huge diff either way.  Buy them and enjoy.
  
Semper Fi SAINT.  May you rest in peace.