The narrower the wheel in relation to the tire, the more likely the tire to "crown", or ride on its center. This reduces contact patch - the area of contact between tire and road - which presents several problems - premature wear at best, severely compromised and thus unsafe performance at worst.
A good rule of thumb is that tire tread width should equal wheel width.
If I get your drift - no, having a wider tire on a narrower wheel doesn't make things any safer. This may not convice you to ignore the siren's song, but it really ought to.