How to Undercoat and Rustproof Car Wheel Wells

by Tom Keaton

Undercoating your wheel wells is a form of rustproofing in itself, since the coating seals off your metal from moisture and the elements. By undercoating, you are therefore doing much to prevent rust. Besides the rust factor, undercoating also serves to reduce road noise, since the coating is a tar-like material. Undercoating the wheel wells also affords a fresh, clean look and enhances the general appearance of your vehicle. And it's an easy job!

Jack up one corner of the vehicle. Remove the wheel. Support your vehicle properly with jack stands; never rely on the jack alone.

Wheel well before undercoating

Using your brushes, degreaser and water, clean any and all debris and oils from the wheel well to be coated. Wear your safety glasses to avoid cleaner splashing back into your eyes. Let the area dry and wipe clean.

Tape and paper off areas outside of the wheel well, to avoid spraying undercoating anywhere but on your target area. Tape off any brake or fuel lines that may be running through the area, along with any wires. You only want to apply the undercoating to the wheel wells (and possibly some exposed areas of the frame, if you desire).

Shake the can of undercoating well. Lay out some rags on the ground below the wheel well to catch any drippings. Put on your gloves, cap and safety glasses.

Wheel well after undercoating

Working in a ventilated area, spray the undercoating in even strokes, using spurt-like sprays to cover the desired area (rather than holding the nozzle all the way down and not releasing).This method of spraying will help you avoid over spraying and messy runs. Spray from a distance of 8 to 10" from the target. Two coats is the maximum you will need to spray. Allow at least 15 minutes between coats to avoid running.

Remove your tape and paper and deposit them in a plastic garbage bag than can be tied off for proper disposal. Include your dirty rags and empty spray cans in the same bag, to ensure the undercoating is not handled by anyone. It is sticky, messy stuff!

Make your way around the car, spraying the rest of the wheel wells. Reattach the wheel in each completed area before you remove the next one, so the car will remain stable and safe.


  • check It is important to wear gloves and safety glasses while spraying, so as not to risk getting any undercoating in your eyes. The gloves will keep the coating off your fingers as you spray. Sometimes the can will drip from the nozzle, since the coating is a heavy product.
  • check The undercoating will run very easily if sprayed from too close of a distance. Applying a coupleof lighter coats is better than trying to apply one heavy coat.
  • check If you encounter a run, you can quickly wipe it off and spray the area again. The undercoating will dry with a textured finish, and small runs or oversprays will go unnoticed.
  • check The undercoating will dry to the touch in a few hours, but it usually will not truly harden until the next day.
  • check It's a good idea to test-spray an old piece of cardboard first, to get a feel for how the spray will be dispersed from the can.


  • close Always support the vehicle with jack stands while working. You may even want to use wheel chocks as well, so that the car cannot roll.
  • close NEVER rely solely on the jack for support.
  • close Always work in a ventilated area when spraying this product.

Items you will need

About the Author

Tom Keaton has been writing professionally since 2007. His background includes experience in mortgage banking, pest control and classic-car restoration. Keaton has also worked as a licensed stock broker.

More Articles