1.25" or 1".
I have a set of 4 aluminum bolt on 1" spacers that would work great for you. I used them to mount a set of 18" bullit replicas. They fit great, but I ended up pulling them out to change up my wheels combo.
If you are interested, send me a PM. I'll give you a great deal on them as I don't need them anymore any they only got used for 1 season. Whatever you do, make sure you get the bolt on style spacer for anything 1" or more. They are much safer.