you should really only use them if the centre hole of the spacer properly seats onto the wheel hub,
and the centre of the wheel properly seats onto the spacer, so that the hub is carrying the load if that make sense?

you dont wanna travel at 200kph+ and be crashing over ripple strips if your just relying on your wheel studs...

but in saying that, ive done it before with no hassles. but probably wouldnt with a heavier car than a 1200

wheels that fit are a better option, you can never have enough mechanical peace of mind when blasting around the track