oh yes it matters.
the c/bore is the center bore. yuh know the hole in the wheek that fits on to the hub.
its this that should take the weight of the car and not the wheel bolts. the bolts are just there to stop the wheels falling off.
if the c/bore on the wheel is too big then the wheel will not run true and the car will handle like a bag 'o' sh!te.
you can get around this if you have alloys buy fitting differnt plastic liners in the c/bore to make it the correct size for your hubs.
thats how i made renault alloys fit my golf.

hope that helps
