There are several issues to consider here. In the first place, there is the question of transmission from the engine/gearbox to the wheels. Most vehicles are designed so that driven wheels run at the same speed, so need to be precisely the same diameter. Otherwise, differentials need to work continuously to compensate for the difference in wheel rotation speeds Exceptions are some models of agricultural vehicles, with different size wheels front/rear. But the drivetrains on these vehicles have been designed to take this difference into account.
In your case, the different size wheels are on the rear axle of a front wheel-driven car, so this is not a problem. Things would be different on a rear wheel drive, or permanent 4x4 vehicle. I have experienced transmission noises on a Honda 4x4 Beagle in similar circumstances.
The second aspect to take into account is handling. Wheels of different widths handle differently in curves, even if their overall diameter is more or less the same. Even different makes of wheel rim can have their influence, e.g. with rims of differing weights. So your car will handle in a slightly different way when going around bends to the right or to the left. If going really hard, the rear will start to slip at different speeds. However, if you drive cautiously and at sensible speeds, this should not be a problem.
Note also that your tyres are in fact a mix of winter tyres (the Blizzak) and summer tyres (the Michelin). They have completely different surface patterns and compositions. You can expect very different handling characteristics.
As a side note, what has been said so far is applicable to spare wheels with different sizes from regular car wheels. These are always marked with specific speed limits: "Do not drive in excess of 80 km/h or 50 mph", "Exercise caution", etc.
Finally, depending on the specific legislation of the country (or state) in which the vehicle is registered, you could very well be foul of the law. For instance, in my country it is clearly specified that all wheels on the same axis must be of the same type and characteristics. Even using tyres of different brands is frowned upon, since wheel sizes may present some variation between tyre manufacturers or even wheel models.
If you are concerned with this situation (I would - specifically with the difference in rim sizes), a simple solution would be to purchase one complete wheel of the same type and brand as the three identical wheels already mounted on the vehicle. You then have four equal wheels to drive on. The different wheel can be re-purposed as a spare, to be used only in the case of a flat as a means to get you to the garage.
