LED array layout... which voltage should I use?

Instead of buying a $40 LED stick, I decided to try making my own. My question is about the resistance. I used this calculator:

http://led.linear1.org/led.wiz

The LEDs are 3.4-3.6v fwd voltage, 30mA fwd current - 75mA max. I used 3.5v, 30mA

with a 12v source, it tells me to wire in groups of 3 (series) with a 56 ohm resistor.

If I input 14v, I get 4 in series with a 1 ohm resistor.

My question is, if I do the 14v wiring, will it hurt to run them on 12v (engine off)?

If I wire them according to the 12v layout, will it burn them up at 14-14.4v?

Or should I just go with an average of 13v? (3 in series with 100 ohm resistor)