Please be aware of the following if you intend hiring either a motorbike or car during your stay in Chiang Mai. The law is the same for other parts of Thailand, but the fines stated are specific to Chiang Mai (December 2018) and may differ in other provinces.
When travelling on a motorbike the law requires drivers and passengers to wear a crash helmet. Failure to do so results in an on the spot fine of 200 Baht per person.
To drive either a motorbike or a car, the driver must be able to produce a current International Driving Permit (IDP) in addition to a current national driving licence. There is an on the spot fine of 400 Baht if the driver is unable to show an IDP.
If the driver is unable to show a national driving licence from their home country, the fine for this civil misdemeanor is currently 1,000 Baht. Plans are imminent, however, to redefine this civil offence as a criminal act with penalties determined in a magistrates court. New fines of between 10,000 and 50,000 Baht and/or prison terms of up to five years are likely to be implemented.
Thailand signed up to the 1949 Convention on Road Traffic, whereby participating countries recognised each other's driving licences for temporary periods, on the proviso an International Driving Permit is obtained prior to overseas travel. The IDP translates a driver's licence into different languages and, importantly, details what class of vehicles the permit holder is entitled to drive. The format and content of the IDP is stipulated by the 1949 Convention and Thai traffic police will not accept any other format as valid. Avoid buying a fake "International Driving Licence" from the internet or from Bangkok's famous Khao San Road along which many fake items can be found. Printed with a grey or white cover, the 1949 Convention IDP contains a photograph of the permit holder and driving licence details.
If you do get stopped by the police for a traffic offence, such as running red light, it is advisable to pay an on the spot fine, even if you dispute whether or not you committed the offence. If you can't pay, or won't pay, the police are within their rights to impound the vehicle and escort you to the local police station. The fine increases significantly, and you may also have to pay to get the vehicle released. If you act in a manner which the police find offensive by shouting, arguing or remonstrating with a police officer, you may well spend a night in the cells and appear before a magistrate the next day, charged with obstructing a police officer in the execution of their duty.
* Check what insurance cover is provided by the vehicle hirer, and make sure provision of insurance is clearly stated within the rental agreement.
* Take photographs on your smart phone of any dents, scratches or other defects. Make sure the registration plate and the brand name of the vehicle are included in your photographs. Obtain the rental company's email address and send them the photographs. Even though you may be given a copy of a form highlighting the same defects, sending an email with photographs means there can be no dispute about the condition of the vehicle when you picked it up.
* Check the fuel tank gauge, and take a photograph to send with the others. Very often, the hire companies do not fill the tank before renting out, but state on the rental form that you must return with a full tank.
* Ask what steps you should take if the vehicle breaks down or is involved in an accident.
* Some motorbike hire companies fail to pay road tax on time. It is the hirer's responsibility to check they are driving a vehicle with the correct road tax disk. If stopped by the police, the driver of the vehicle is required to pay an on-the-spot fine of 200 Baht if the tax disk is out of date. As the tax disks are written in Thai, and use the Buddhist year (currently 2561), it is not easy for a tourist to check whether or not the tax disk is out of date for themselves. Ask the staff when you get back to your hotel/guest house to check the tax disk for you.
* Motorbike and Car Hire companies always require sight of a valid passport when renting a vehicle. Some may ask to see a valid driving license. Others may want to retain a hirer's passport for the duration of the vehicle hire period, or ask for a large cash deposit instead.
* It is inadvisable to leave a passport with a vehicle hire company for two reasons. Firstly, it is not unknown for passports to be cloned and sold on the dark web. Secondly, Thai law requires all foreigners to carry a valid passport with them at all times. Most tourists prefer to leave their passports in their hotel safe, and, for most of the time, having a photocopy of their passport to show the police is accepted. However, if stopped by the police for a motoring offence, an additional on-the-spot fine may be charged if an original valid passport cannot be produced.
* Everyday of the year at least one tourist enters hospital in Chiang Mai because they have fallen off, or have been knocked off, their rental motorbike. It may look cool to drive a bike without a helmet, wearing shorts, tee shirt and flip flops. But please wear a helmet, long pants, shirt/top with long sleeves, and covered shoes. If you come off the bike, these precautions will provide some protection from the impact of skin being dragged along a concrete road.
* If you are involved in an accident, do not move the vehicle until after the police arrive. Moving the vehicle can invalidate, or substantially reduce an insurance claim, should the police rule you were responsible for the accident and there is no evidence to prove otherwise.
* If you are in fit state to do so take as many photographs as you can of the vehicle(s) involved in the accident from different angles.
* Always make sure you have a business card in your wallet from your hotel/guest house when driving. If you have an accident, the police will at least know where you are staying and can advise your hotel and your embassy of your fate.
* Assume motorbikes and other vehicles will undertake you on the left hand side of your vehicle. This can be quite alarming if you are not used to this
* Assume at every road junction, vehicles will turn into your path without looking first.
* If you are at traffic lights waiting to go straight across, don't zoom off in a racing start. If you do, you will crash into a Thai motorcyclist who appears from nowhere and drives straight across your path to turn right.
* At some traffic lights you are allowed to turn left, even though the lights are on red, if you can do so safely. However, the signs that allow you to do this are written in Thai. The best advice is to follow what local drivers do. If you are at the head of the queue, don't move until the cars behind you honk their horns, indicating you should turn left.
* If someone in a truck or coach tailgates you, slow down and let them overtake you. Don't try to out pace them or make rude gestures. Speeding big trucks can do a lot more damage to you and your vehicle, than you can do to them!
* Flashing headlights at another driver means different things in different countries. In the UK it means "You go first and I will wait until you have completed your manouvre." In Thailand it means the opposite, "Get out of my way, I am not slowing down, and I am heading straight for you."
* Always be sure to give cyclists and trishaw drivers a wide berth.