They're wrong or had terrible back spacing. I run 245s and have never rubbed, hit or even come close. It's perfect.
I have also seen 265s on the front of a 1970 Challenger R/T S.E. - stock. Seen it in person several times (car below).
I'll state this one more time....3 cudas, all factory 15 X 7 rallye wheels with 245-60-15 front tires, and ALL three rubbed the inner frame rail to some degree. I'm not wrong and it's not terrible backspacing....thats a factory 4 1/2 inch backspace if i remember correctly. It's pretty obvious that every car is going to be a little different and maybe you get away with the slight rub and maybe it just clears. This is a rub at full lock BTW. Even the alignment of the front end can make a difference, as well as tire manufacturer. Tires can vary slightly from manufacturer to manufacturer. Best bet is to try a set first if you can get ahold of some tires/wheels in the combo you are considering and see if they rub.
Heres another consideration...one time i was pulling into a space at Carlisle and the car had to back up a hill over the lip. (remember the year E-bodies were up on the hill about 3-4 years ago?) I had the wheels turned as i backed in and the tire caught the wheel well trim and bent it. Not my imagination, had to take it off and straighten it out. That was a 245-60-15 BFG T/A radial on a 15X7 stock rallye wheel. This was my red 71 hemicuda clone.
Can people get away with 275's or 245's on the front...yes they can. Custom offsets can help get more tire clearance, but the fact is if you run 15 X 7's with factory backspacing and 245-60-15's you run the chance that your tire will rub the frame rail or in some instances catch the wheel well lip. Only way to be sure of clearance is to check it, and not just sitting still in a parking lot.