That depends on how well your car is cooling. When you are out driving, what does the temperature gauge read?
The thermostat only controls how cold your car can get in winter. It will not keep your car from getting hot.
My 1982 corvette has a 160 thermostat in it, but the car will hit 220 when i'm driving at 70 mph or faster. And yes, the temp sending unit and gauge are accurate.
If you are driving a lot in winter, then put in the 185 so that you are at the correct temperature in winter.
If you only drive in summer, and your car is going to run hot like mine, then you can put any thermostat in you want. Last summer i took the thermostat out and i still hit 230 accelerating up a hill.
(The DeWitts radiator is in the mail, so soon my problems will be gone)