What's "wide" to you? Some think 28mm wide tires are wide, others want to go >2 inches.
Overlooked (because they're harder to find) are older, low volume English framebuiders, such as
Gillott and
Ephgrave. I pick these two as I've done 650b conversions with them, 42mm wide tires as the goal (met). On both of these frames I have no idea what frame tubing was used, but clearly they picked some of the lightest tubing available at the time. 650b conversions are a great way to fit wider tires into vintage frames.
Note that a frame that weights a half pound lighter won't make much difference at all from a heavier one just on weight itself - drink a third of a full water bottlee and you've lost half a pound. The frame, however, will be much more lively and compliant due to thinner wall tubing.