18" Spiders - front and back the same?

[LaserTam]

Maybe a dumb question, but are the 18" spiders the same size front and back, in terms of offset etc? Will be having both offside wheels referbed and just want to make sure whether it matters what tyre goes back on what wheel.

[LaserTam]

Cheers chaps. Hopefully the tyre fitter can work that out all by himself, but I may just check