If you let down tyres for a causing a traffic offence then only let down ONE tyre, ideally the front drivers side one, and let it down fully all the way to flat.
This will mean that:
- The driver should spot the problem before they get in
- If they don't it should be very obvious as soon as they try to drive
- Most importantly, they will have to swap the tyre with the spare and then pay a garage to 'fix' the flat tyre.
You will have made your point, nothing more needs to be said
If you let down all the tyres it's then obvious what happened and they just pump them up again.
If you partially let down tyres, that can be very dangerous, not just for the driver but also totally innocent people around.