if your 95 ex wheels are stock they should be 14's, that is the standard size of civics unless you have an 99-00 si, then they would be 15's. just look at your tire size and you will know how big your wheel is. the last number of the tire size is your wheel size.
All 96-00 Civics had 14" stock rims, except for the 99-00 SI which had 15's. I believe the 92-95 Civics all had 14's as well except for the DX which had 13's (someone correct me if I'm wrong).
17's will fit just fine on all Civics going back to 92. The things to watch out for is how wide they are. 7" wide will rub very occasionally only if there's extra weight in the car or it's dropped really far (3" or more). 7.5" will rub a little more than the 7's but it can still be done. Do not get 8" wide rims. They will rub inside the wheelwells like mad. You can even go up to a 19" rim on 96-00 Civics but it gets kind of hard to find one that's only 7" wide.
If you plan on dropping your car, you're very likely going to rub if you go with a 17" with a 215 or wider. Depends on the drop, width and ratio of the tire, etc. but I bet you'd rub. If stock ride height, things should go smoothly for you.
a 95 civic EX comes stock with 14" wheels. if you go 17s i would recommend going 205/40/17. these are pretty much a standard tire size for that big of a rim. i personally ran that size on my integra. going with a 215 would be a little too wide. you'll have to roll your fenders and what not. but probably you will rub more then likely. but just stick with 205/40/17 and you'll be happy and will not have problems. the offset of the rims have something to do with it too. just ask if you hav emore problems