I have 31x1050s on mine and with a GPS mine is 16% off (50=58 mph, 100+116 mph, and so on). I have checked what my speeds should be at differant speed limits and in 100,000+ miles (116,000+ corected) I have recieved 0 tickets. Just drive a little under the limit and you should be fine.
your speedomter isn't just 5 or 6 MPH off, the faster you go the more its off.

Dennis

95 Sportage, gone but not forgotten.
98 Jeep TJ, 4" Zone springs with RC Long arms, Ford 8.8", 4.56 gears & Detroit locker rear, D30, 4.56 & Detroit Trutrack front.