which maps do the qualcomms use?

I would never go by strictly a GPS for routing. You need to route yourself according to a current Motor Carrier Atlas and then program your GPS to follow that route. Not doing so could result in a major mishap or ticket at the least.

 

well i use Rand Mcnally 700..it has yet to steer me wrong,but when it wants me to cut up or over on a US highway i always double check with the motor carriers atlas just to make sure i am legal on that highway and i wont run into any surprises so to speak. it will put a little dent in your pocket tho.but in my mind well worth the money.and it is constantly being updated by Rand Mcnally,and its been for free so far