Safety factor when designing rear suspension.

[Rhino]

When designing a rear suspension, what is the commonly accepted "safe" safety factor. I have a tendency to over build everything I touch, and I'm trying to get out of the habit. I just want to insure I don't take it too far.

Looking at a few threads on CC's I tend to see people talking about a design giving them a "good safety factor" although this never seems to be qualified with a number.



In a design I'm currently working on I estimate a 2 to 2.5x safety factor when comparing my loads to the yield strength of the native steel. I have yet to decide on rod ends, although I would look toward something with a similar safety factor.
Is 2 to 2.5 enough for a street driven vehicle? It seems a little low to me given the repeated compression/tension loads the links will see. By stepping up the tubing size slightly I can get around a 3x safety factor on all links. I feel more comfortable with that, although I then begin wondering if I'm trying to overbuild again.