Do I need a different brush for the wheel face, the barrel, and the tyres?

Yes. A tyre brush (stiffer bristles) is correct for tyres and wheel arches but is too stiff for painted wheel faces and will mark them. The wheel face needs a brush with flocked bristles or a rubberised edge to protect the clearcoat on accidental contact. Barrel interiors need a long, flexible inner-spoke brush (a Wheel Woolie-style brush) that can reach through the spokes. Using the wrong brush on the wrong surface is a common cause of fine scratches on alloy faces.

Are expensive wheel brush sets worth it for a home detailer?

No. For a normal household car, the minimum viable kit is: one inner-spoke brush for barrels, one wheel-face brush with flocked bristles or a rubberised edge, one small narrow brush (around 16 mm, such as the ValetPRO sash brush) for wheel nuts and tight corners, and one tyre scrubbing brush. A wheel face mitt is an acceptable alternative to the face brush if speed matters more than reaching round the back of each spoke. You do not need a full Wheel Woolies set.

Is the EZ Detail brush safe to use on gloss black or painted sensitive alloys?

No. The EZ Detail brush causes marring on gloss black wheels. For gloss black or any painted sensitive finish, switch to a microfibre wheel mitt or a wool equivalent instead of a bristle brush. The EZ Detail brush is well suited to standard painted alloys, since its nylex bristles are chemically resistant and the rubber tip protects the alloy face on contact. Store it hung up and dry between uses to maintain bristle condition.

Should I load the brush with wheel cleaner before touching the wheel?

Yes. Pre-dose the brush with wheel cleaner before making contact, rather than relying only on what you have sprayed onto the wheel. A dry brush drags and lifts grit across the wheel surface; a primed brush glides and pulls dirt into the foam. Apply this to both the barrel brush and the tyre scrubbing brush. Never go into the barrel with a dry tool.