Cone Nuts?

you don't need to get them off on both sides. Just undo one side and then pull the axle through.

Need to replace the bearing so need to get both sides off? I think the shop that built the wheels tightened them up too much!

You still shouldn't need to take both off. Once one side is off, you pull (sometimes knock) the axle through the other way. Than you've got access to both sets of bearings.