Wire Length

So this is a bit of a silly question but here it goes,

So I have a usb Hub that has an extra power supply,

this power supply lets off 12 Volts 3 Amps but the wire on it is kak short and I would like to make it longer,

So I want to extend it by 2.5 meters, should I use the Same thickness of wire or should I use a wire thinner than the original one ?

Regards

Byron