Occasionally, while driving on the highway, you'll be asked to pull into a weigh station for verification and will receive a fine for skipping it. This is somewhat random and will usually happen during longer drives through major cities. There's a weigh station near the Nevada border that you can use to try and trigger the event if needed but it's more likely you'll get this one naturally.
Once triggered, you'll have to pull into a weigh station and drive up onto the scale where there will be a marker waiting. Drive up and confirm the scale and the achievement will unlock.