scooter tire questions

[RyanosAlien]

Hey,

My current scoot is labled a alien longbo, aka roketa aka every gy6 but my tires size reads 4.00 x 12 my question is if I need to replace them what size do I need to ask for or do I just tell them the 4x12 size and I actually would like to go bigger these little tires makes me personally feel real unstable .