Ski/snow goggles should fit comfortably over your helmet.

Really they shouldn't be pinched or feel tight on your face. Goggles that fit correctly over your helmet should be able to rest comfortable on the top of your helmet.  However, when pulled down to cover your face, they shouldn't feel too tight.

There should be enough adjustment length in the goggle strap to guarantee that the goggles will fit any size helmet. There is a strap in the back of the helmet that holds the goggle strap in place. Make sure the goggle strap has adjustment room there also.   Ask if you can try them on or send you measurements of the helmet.

Enjoy your trip.