They are an interference fit to the hub so should stay in place when you remove the wheel.

My spacers bolt to the hub, then the wheel to the spacer.

20mm_spacer.jpg
 
ive just recently bought a full set of 20mm's and these dont bolt direct to the hub the have extende3d wheel nuts the reach all the way thru to the hub
the guy who sold them to me said that is safer that way with 20mm or above, but he would wouldnt he :)
 
here's my LC on LCR alloys. I've spaced it 15mm rear and 10mm front with hubcentric spacers. The car looks so much better for it and feels more stable.

DSC01129.jpg

DSC01124.jpg

DSC01119.jpg

DSC01121-1.jpg

I dont get any rubbing but i'm only 15mm(ish) lower on eibach pro springs

I must say this looks spot on imo :)
 
ive got hubcentric spacers "FKs" theyr either 20mm/25mm on the rear and 10mm on the front , everyone says it looks amazing and phat from behind =) handles awsome
 
Jimbob you have utterly confused me dude i dunno what you mean. Please rephrase matey.

Your original wheel bolts now bolt into the spacer, not the hub. If your original wheel bolts used to bolt 11mm into the hub, and you get 10mm spacers of this kind, your bolts will go all the way thru the spacer and foul the hub. Make sense?
 
15mm are a spacer with longer bolts, they are placed on the hub the the wheel on then the longer bolts used.

20 mm have the spacer bolted to the hub, and then wheel on and then you re-use your standard bolts you took off.