Just so you know:
Radar in moving mode has accuracy of +/- 2MPH
Radar in stationary mode has accuracy of +/- 1MPH
Car speedometers for pacing accuracy of +/- 2MPH
All items, radar & speedo require calibration checks
periodically. If they were not done recently, you may be able to beat the ticket. If he got you with Laser, you are pretty much a dead duck as far as beating it.
In your case, he got you at 15MPH over the posted limit.
You might be able to get it down to the next lower range, which in NJ is 1-14MPH over .. Fine will be less, but California will still add 1 point for the speed ticket and 1 point for the Unsafe Passing Ticket