Help! Difference in tires for 95 coupe

[b jennings]

what is the difference between a P285 40 ZR17 100Y and a P285 40 ZR17 100W?

 

[Tuna]

what is the difference between a P285 40 ZR17 100Y and a P285 40 ZR17 100W?

The difference here is the "speed rating" for the tire. The last factor (100W or 100Y) indicate the "load rating" and "speed rating" for the tire.

W = 168 MPH
Y = 186 MPH

Check out TireRack's tech page that discusses this.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=35

If you never, ever drive your car fast, you could probably get by with "H" rated tires but if you forget about that and put your foot into and exceed the tire's speed rating, you could be looking for trouble.