What should a truck driver do when approaching an overhead bridge or tunnel with an advisory height clearance sign?

1. Drive through quickly; height signs are always 2 meters taller than reality
2. Know the exact loaded height of your vehicle, slow down, and never attempt to pass under a structure if clearance is less than or close to your vehicle's total height
3. Deflate all tyres by 50% while driving under the bridge
4. Sound the horn to raise the bridge height