I was afraid that might be the case. Thanks.
The best you can do is compare what the speedometer reads compared to a gps and adjust accordingly. With 31" tires, my truck is traveling about 3 mph faster than what the speedometer is telling me on average. So, if I stay a little bit under what the speedometer is telling me, I'm close.
If you are worried about getting a ticket, most police officers will give people a buffer. So, in my case, even if I travel at the speed indicated by the speedometer, I'm still safe from getting a ticket. Generally speaking, it should be the same for you. Granted, there are some reguons where buffers are not granted for reasons ai won't go into because of politics, but if you know that and know the general error of you actual speed to what the speedometer is tellin you, you should still be good. Also, a ticket for traveling a couple of mph over the speed limit will be thrown out or something will be taken away if you show up at the magestrate's office to contest the ticket.
Traveling out of state tends to throw a monkey wrench into the works but if most people are traveling faster than you or if you are traveling with the speed of traffic, while not blowing by everyone and/or weaving through the traffic, you should still be good.
Let the speed demons be the rabbit that flushes out the speeding tickets. There are plenty of them out there and there seem to be more of them every day.
