A good compromise will be a 7 PSI cap. That will allow a 21 degree rise above the atmospheric pressure boiling point, or 233 degrees at sea level. Any normal operating range in the 200-215 range will be perfectly safe, and you can run a 180 degree thermostat that will actually keep you warm if you drive in the winter. if you run a 160, invest in a good goose down vest and some gloves!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!