I apologise in advance as I'm sure it's been asked before. I have a standard uk 1999 Impreza wagon turbo. The wheels are 16inch. What's the other numbers that I need to take into consideration when buying a new set? Is the bolt pattern 5x100? What's offset all about? I'm not worried about going too much bigger I just want a set of 17s possibly gold. 

Many thanks

Frank 

I think this is the original wheel size for your motor

15" (diameter of wheel) x6.0"J (width of wheel) offset et55 (offset of wheel centre from hub) PCD 100 (distance between the wheel studs / holes)

here is a link to show you impact on look / setup of different wheels.

http://www.1010tires.com/Tools/Wheel-Offset-Calculator

Hi mate mine are 16" the 5 spoke style.