Re: Skate Board Question - Bearing Spacers
The short answer is get the spacers.
The long answer is that you don't really need them. In the time I spend skating I've gone through my fair share of bearings. If you put your wheels on without spacers and don't overtighten them you shouldn't really have any problems, as bearings seem to be quite strong, and in almost all cases they'll start to wear out from dirt getting in them long before you blow one out riding it.
However, there's a few advantages. The spacer means you don't have to worry about tightening them properly, you just put them on fairly tight, since a properly sized spacer (with washers, don't forget the washers) will make a solid connection throught the nut, outer inside race, spacer, inner inside race, and truck hanger (also, the washers). Also, the load on each wheel during a turn will be applied to both bearings on each wheel instead of just one. I don't know how much of a difference this makes, but since they're so cheap, I'd say get them.
Also, longboard wheels are sometimes wider than regular ones, so don't torque down on those nuts unless the spacer is actually properly sized for the wheels.