Oh, don't get me wrong. I am not saying that you
will have a problem guaranteed! Or that you
will have an accident as a result of this tire selection.
The thing is that stretching tires can make them a bit more unsafe, and less tolerant of situations where normal fitment tires might do fine.
For example, hitting a bad bump or pothole on the highway
might pop the tire off the wheel if the bead is not seated properly. Where a properly fitted tire would not have a problem! At speed, this could be dangerous.
And, if (a big if, of course) you get in an accident and end up in a lawsuit or insurance settlement situation, the opposing attorney (or insurer) could make a stronger case against you because of a less than safe tire situation. Remember that you could be an excellent driver, and the other person who hits you could be at fault ... but you could lose that not-at-fault position in a heartbeat.
Regardless of all that, remember that using too wide a tire for a given wheel, and then putting normal pressure in the tire, can actually lift the edges of the tread off the ground so that the width of the contact patch of the tire on the ground could be less than a correctly fitted tire. Meaning that you could have
less of the tread touching the ground than if you had used correct width tires, and handling/performance is degraded.
Putting on correct width tires for a given wheel width optimizes the performance of the tire - going outside the limits (either too narrow or too wide) by a lot, can potentially decrease performance and handling.
So ... What is your reason for putting on wider than normal tires for that particular wheel width?
(BTW, ultimately, this is still your choice to do this, of course! But people who worry about performance and safety are not likely to endorse it.)
Z