What offsets do I want for an 18" wheel going on a Boy Racer Kit?...The Shelby Razors have a 12 and 24 offset?

Thanks

 

The 24mm Razors will put the wheel in line with the top edge of the wheel well (maybe a little over depending on tire width). The 12mm Razors will extend the wheels beyond the wheel well edge by about 1/2 inch. It just depends on the look you're going for. IMO the 24mm look on the Boy Racer Kit would be sweet.