Montana, who led the 49ers to four Super Bowl victories from 1981-89, admitted to his team's wrongdoings and referred to the "Deflategate" scandal surrounding the current Patriots quarterback as "no big deal."
"Everybody is trying to do something different," Montana told the Pittsburgh Tribune-Review .
"Our offensive linemen used to spray silicone on their shirts until they got caught. Once you get caught, you get caught. Period. It doesn't take anything away from Tom's game. But how long has he been doing it? I don't know."
Montana added that he never realised taking some air out of the football would make a difference.
Had he known, he would've done the same thing the Patriots are accused of doing during January's AFC Championship Game because he "couldn't throw a wet ball to save my life."
An investigation by attorney Ted Wells found that Brady was "generally aware" he was using underinflated footballs and was suspended four games by the league.
"It is one of those things that is a rule, right?" Montana told the Tribune-Review .
"It might be a dumb rule, but it doesn't matter. He didn't deflate them himself, but you can pick up the ball and can tell if it is underinflated, overinflated or what you like.
"Everybody is afraid to say it, but if the guy did it, so what. Just pay up and move on. It's no big deal."