Rim width. Which is best....

[Dino86]

I have two sets of 14" rims: one set is 6" and he other 5.5" wide. Both are equipped with 185/60R14 wintertires which I will use in regularity rally.
Surface is one day 95% tarmac (probably wet and slippery), second day is almost 100% gravel.

So, to all the experts out there, which is the best rim width to use and why?

I guess more narrow is better on the gravel since it might give more sidewall deflection? And I guess it's safer to avoid tire coming loose from the rim.
But, is the wider much better on asphalt?
Can I compensate the smaller width with increased tire pressure?
Or, since I'm not using competion tires, difference between 5.5 and 6" is neglectable?
Anyone has some experience with it?