Actually it's the opposite, narrower front tires and fatter rears induce UNDERsteer. Think about it, you'd have more grip on the drive wheels than the steered wheels. That's a very odd tire staggering, seldom used for handling unless it's an old school Porsche 911 Turbo (a naturally tailhappy design)
Having said that I disagree with the go to answer regardless because sway bars are not the proper answer for heavy handed handling changes because they A. make the suspensions behave more like solid axles the fatter they get and B. equal doesn't equal equal. Everyone simply ASSumes because these cars are biased for understeer stock it must be the sway bars fault.... not really taking into account the 58/42 weight bias, springs and shocks or soft durometer bushings, or the toe compensators - literally there in the words of an MN12 project engineer - to induce understeer!!!