Lets break this down....
You've bought Tyres that don't fit your current wheels.
Options are to buy tyres that fit, or (the harder option) buy wheels that fit your tyres.
So you choose to buy new wheels,
The simplest option would be to buy a set of Rays. Rays are the wheels that most Zeds have as they are the factory optional extra.
Those ^^ Are rays. It's just a brand like Nike, Adidas etc.
The rays will fit your tyres perfectly.
Options C - Find a set of wheels that are Between 8-9.5J Wide in 18's.
If you are not bothered about the wheel filling the arches, then just remove the wheels spacers.
Easiest option, if you like them of course, is to find someone selling a set of rays to buy.