Will my tires safely hold 60 psi?

They will hold that pressure fine as long as you don't add a lot of weight or have too much spirit in your driving. However, over-inflation will cause uneven tire wear that can cause a potentially dangerous blow-out.

If these are high-performance low profile tires then you would rather have the pressure around 60-75 psi to improve gas mileage around town. You would only want to run the recommended psi if you are racing or driving in conditions that decrease traction. (remember that is if you have high performance low profile tires)

Something you should know about the max pressure on a tire:

***It is the maximum safe pressure that the tire can hold, as stated by the manufacturer. That does not mean your car will perform safely with that much air pressure in it.***

Is this what people are doing to save gas?

They may hold the pressure but the car will be a pig to control because you will have drastically reduced the contact area.

While it looks good on paper it just would not work in practice

It is not arithmatic. It has some thing to do with Material science. The material may not withstand or not designed to withstand sucha pressure for long even though they are designed with a safety factor of 3 but not for continued load and pressure.

never pressurise when not recommended.

I don't think your tires would hold that much pressure for very long. You really shouldn't over inflate the tires any more than the vehicle's manufacture suggests.

Good math, bad logic!

all things look great on paper...in the real world things dont work the same..

NO!!!!!!!!!!!!!!!!!! they will blow out.