www.willtheyfit.com
I am currently running 15mm spacers with the oem 18" wheels. I have my rear fenders rolled because my previous set of wheels required it, but now with the OEM wheels and their 50mm offset, they clear no problem. My car is lowered, and I do get a little rubbing in the wheel wells when making hard U-turns but the fender lips clear no problem. I cannot speak for the rears as they are already rolled, but they shouldn't have any trouble clearing the fender.
I can tell you that a 19 x 8 +35et wheel with 225/40/19 tires will get gashed by the un-rolled rear fender (don't ask). After running the numbers, comparing the 19" wheels to where the factory wheels with 15mm spacers sit (effectively changing the offset to +35), you shouldn't have an issue. But every car can be a little different. Go out to your car with a ruler or measuring tape and check the clearances. Keep in mind the top of the wheel/tire will swing inward slightly upon suspension compression, so take that into account.