For a tire to hold its inflation, a clean, smooth rim surface is essential. Environmental factors, salt, lubricants, water and other contaminants can cause damage to the rim’s surface area over time.
Steel and alloy wheels often will show signs of rust and corrosion on the inner bead surface. This is especially true of alloy wheels. The rough surface can prevent the tire from sealing completely against the rim.
The goal is to get the surface to be as smooth as possible. The best way to deal with rust and corrosion is to scrub it off.
Scrubbing the surface by hand with a wire brush to clean signs of corrosion is recommended. For a more aggressive approach, some shops use an angle grinder fitted with a knotted wire brush. No matter the method, care must be taken not to scratch or damage any chrome or protective clearcoat on the face of the wheel.
Note that aluminum wheels are softer. Instead of risking damage to the rim condition using a wire brush, a polishing compound is a better option for cleaning any corrosion.
If the bead contact area of the rim isn’t able to be cleaned completely, using extra liquid bead sealant can help compensate. If the rim condition is still questionable, recommend that the wheel be replaced with one in better condition.