Spacers have to be certed, and meet a few guidelines (i'd copy and paste, but the LVVTA PDF wont allow me to

)
But pretty much:
-Maximum of 20mm away from the hub;
-Be set screwed or attached by another secure method to either the wheel or hub face;
-Be manufactured from a solid block of suitable material;
-Have 2 machined or die-cast surfaces that are parallel, and contain minimal indentaions or irregularities;
-Be fitted as to ensure the wheel locates snugly over the hub spigot so the hub carries the weight of the wheel assembly instead of the studs, or where there is a mis-match between the hub spigot and the wheel centre, a close tolerance fit centre bore locator must be provided;
-Maintain, with the spacer fitted, not less than the minimum required amount of wheel stud or bolt engagement.
This is either
-Not less than the diameter of the stud thread
-With a 12x1.5 stud - 6.5 turns
-With a 12x1.25 stud - 7.5 turns
-With a 14x1.5 stud - 7.5 turns
Perhaps a mod should FAQ these standards? Seem to be asked now and then...
The PDF about wheels and tyres is
available here
I actually run stupidly large spacers on the back of my GT4 (25mm), and my 7" wheels arent at the guard yet. Seems like ill have to make them smaller, or buy some better-offset wheels
