[mkgmap-dev] Speed limit

If I set my Zumo660 to simulator mode and then let it simulate a ride I see wrong speeds simulated at times. The speeds based on road_speed tags work fine. When simulating riding on a road with a speedlimit=90 tag the gauge on the GPS says 100 and when on a road with speedlimit=50 the GPS shows 60. Any ideas of what is wrong?