Do tuk tuks charge extra for large luggage.

Official metered tuk tuks do not technically have a legal surcharge for standard luggage. However, if your suitcases are so massive that the driver has to physically strap them to the back rack using bungee cords, it is customary and highly polite to offer an extra 100 to 200 Rupees for their physical effort, but they should never demand double the entire fare.