245/35r18's are shorter... it'll probably feel like you've put rft's back on. i'm not so sure there won't be tramlining either. as for vanity, it'll look smaller (albeit by 1/8") in the fender opening.
honestly, dubbedown... you'll just have to try it. one thing i've heard works is to head down to your favorite tire shop and see if they have any takeoffs that they'll let you test fit. they won't let you drive much (for obvious legal reasons), but it may be a cheap alternative to buying tires you find you can't use. 245/35's are not common though, so it may be difficult to find a set locally, if even new.
are you running 255/35's on the rear now? is it feasible you could swap one to the front just to test the car's static clearance? that way, if it works parked, the confidence to try a rolling test squared will be bolstered...
