You will get better overall handling from a 40 series tire than a 30 series in the same width unless maybe you are on a road that is as smooth as glass. Like stated above, the width of a tire makes a huge difference in the fatness of the sidewall. A 285/30 has a fatter/larger sidewall than a 225/30...you can easily tell by just looking at the two tires even though both are a 30 series tire.
2012 Audi R8 V10, 6MT, Suzuka Gray, Capristo X-Pipe, Klassen M52R, GMG springs, R8 GT tails, Satin Black badges
2012 Audi A6 3.0T Prestige, Moonlight Blue
2015 BMW X5 35d, Mineral White
Previous: 11 e82 1M, Several 911's & M3's