This simple instructable will show you how to make some quick and dirty hypermiler hubcaps out of recycled coroplast signs. I got my signs for free, once you keep an eye out for it, the corrugated plastic can be found easily.

WARNING! This modification will reduce the rate at which your breaks cool by cleaning up the airlfow around the hubs. This can reduce their effectiveness if they over heat. I experienced it in the mountains when coming down but every vehicle is different so check to make sure they are not burning hot every so often. I also employ hypermiling driving techniques so I use my brakes as little as possible to conserve energy.

The Materials you will need are:

- Enough Coroplast to cover your wheels

- Zipties. At least 8 inches: the longer they are, the easier it will be to install.

The Tools you will need:

- Marker

- Scissors

- Drill and a hole saw that's slightly bigger than the lug nuts

- Spare Tire for tracing purposes

Step 1: Cutting the Circles Out

1. Take your spare tire and lay it over the coroplast. Trace inner metal circles onto the plastic so that they fit in the hub.

2. Try to use the space efficiently; I managed to squeeze two caps into one sign.

3. Cut it out and make sure it fits, trim where needed. A press fit is better as it will help to keep it in place.

Step 2: Cut the Lug Nut Holes and Air Holes

1. With the circle inserted into the spare, flip it around and mark holes where to drill.

2. Drill out the holes for the lug nuts. I used a 1.25 hole saw. This gave me enough clearance to stick a breaker bar in and remove the wheel.

3. With the cap on the wheel, mark out where the inflator valve is and cut out a hole.

Step 3: Install the Caps

1. Drill out holes for the zip ties to go through. Depending on your hubs, the placement of the holes will differ.

2. Thread the zip ties through the holes but do not tighten them. Attach only the first one or two notches in the zip tie. This will give you enough slack to thread the rest of them through.

3. Once all the zip ties are threaded through, tighten them until the hub is snug and won't wiggle.

4. Trim the excess off the zip ties.