looking a set of wheels and they have these tires on them, tirerack suggest a 40 series tire, can I get away with the 50 on a 96 hatch.

seams like people are using anything from 40-55 series on their 16's

 

The Tire Rack is right; 205/40-16 is the best matching 16" tire size for a '96 Civic hatchback.

Here's my advice. If you like the wheels enough that you would want them for the price being asked even if they didn't have tires with them, then buy them and try them out. If you put them on your car and they rub a lot - they might; they're an inch and a half larger in diameter than your stock tires - then take them off and sell the tires on ebay or in the marketplace forums here; you aren't really out anything if you don't get much for them. If they work on your car without rubbing excessively, then go ahead and use them until they are used up, then when you need to get new tires get 205/40-16 to replace them with. (You can also use 195/45-16.) Remember when using 205/50-16 tires on your car that they are 6.3 percent larger in diameter than your stock tires, which means your car is going to be going faster than your speedometer says - if your speedometer is accurate now, then you will be going 53 when it says 50 - so don't get a speeding ticket as a result.

Don't pay attention to what other people are using, because (a) the diameter depends partly on the treadwidth, and (b) a lot of people use tires that are not the best size for their car, because someone not very knowledgeable told them it was okay.