Knitting rib, which side is the wrong side?

[bebendum]

I'm knitting a hat starting of in ribbing, then i have to change stitch and it says "work in rib for 6 cms ending with a wrong side row"
I have 55 stitches, so one side i finish with a purl and start with a plain when i start a new row, the other side i finish with a plain and start with a purl. Which side am i supposed to start the new stitch on?

Thanks

[suzeeq]

Ribbing is reversible, so you decide which side should be the RS or WS, whichever looks better. Once you've done the 6cm, call it the WS row.

[Knit4Pie]

Suzeeq is right, but I'm more anal than that (LOL). I just watch my cast-on tail.

Unless the directions say otherwise, I consider my first row to be the RS. When I start, I check where the tail is, which is usually at the start of the row, since I prefer the long-tail cast-on. I go from there. At the end of the 6cm, I'd make sure my tail is at the beginning of where I'll follow the new directions.

Hope that makes sense!

Oh, if for some reason I can't see the tail or what have you, I'll sometimes put a st marker to act in the same way. Or tie a different colored yarn around the side.