Tires: Tire mismatches all around, rear axles, sized tires

Question
My existing tires were down to the wear bars, so I recently replaced them.  And since I plan on replacing the car sometime next year (its a 97 sunfire with the 15" wheel package), I just got whatever was cheap from a local used tire guy.  But now I'm wondering if saving a buck was worth it.  This is what he put on:

The front end has 2 matching winter tires that are P195/65R15 (the size my vehicle came with).

The rear end has 2 mismatched all season tires, which he said should be all right because the tread patterns and wear are similar.  What I didn't notice until later was that they are P195/60R15.  When I called to ask about that, he said the only difference is that my speedometer will be inaccurate (when showing 60mph, my actual speed will be 58mph or so).

Doing a bit of research shows tire manufacturers strongly recommend against different sized tires on the front and rear axles (unless the car came that way) -- are they just scaring people away from going the used tire route, or have I put myself into serious danger?

Thanks,
Rick

Answer
Rick,

First, the 195/60R15's are smaller in load carrying capacity, and that's a danger in and of itself.  Lower load carrying capacity increases the risk of an overloaded tire failure and those sometimes have tragic results.

Now to the issue of the mismatched size.  It is obviously better to have 4 of the same tire.  That way the vehicle is balanced.  If not, when you slam on the brakes - particularly if you do it in the middle of a turn - the vehicle may try to spin.

Now to the risk assessment.  The problem here is that there is probably a 1 in 1000 probability that something bad will happen.  The question is:  "Is that enough of a risk for you to do something about it?"  Please bare in mind that there is a probablility within that 1 in 1000 that you will not survive the accident.