If you can stick your index finger between the calliper and the rim you wont have issues at all. Our stock 17in rims down here with our larger 13in front discs have so small a clearance I cant even jam the tip of my little finger in there. To be more technical, we only have about 3/16in average gap. Hence why we cant go smaller than 17's (some 16's will fit, but need around 3.5in backspace like you, though would get pulled over by the cops before the first corner!)
Cheers from Downunder, Dave.
2010 Dark Charcoal Pearl 'Renegade' pack (includes dual top options, 17in alloys, side steps etc).
2.5in Flexy springs, Bilstien 5100's, Teraflex rear trackbar bracket, Synergy front and rear sway bar links and front disco kit, Synergy steering damper relocation bracket, AEV front drop brackets, ARB front and rear bar, 10,000lb rope winch, Britax Xray Vision driving lights, GME 3440 UHF radio.