I'd go the chip first then bar.
Why? - Because the you may already lose a bit of pwr from those tyres and then if you add the extra weight of the bar on it'll be even worse!! Go the chip then the bar I reckon!!
Also, if you have the cash to get the chip, do that first then go driving around dusk with the missus and when you just miss a roo (after you have been actually unbeknown to her, looking for one ) say to her, 'Geez mate I really should get a bullbar on this thing before I do some big $ damage' , she'll agree and want you to do it straight away.
Easier to do that than trying to justify the expenditure of a chip a few mths down the track!!
Hell, I haven't been married for 10 yrs yet and I'm already thinking this stuff up.....Hate to see my form after 25 yrs of marriage!!