Smooth wheel covers

Weather Spotter's cover

Introduction
Moon caps or moon eyes, as they are often known, cut down on aero drag, and can even look pretty cool. The amount of drag reduction varies between different vehicle and wheel styles.

They can be made DIY style with things like pizza pans, or bought at various online retailers.

Some modders will also use clear tape over OEM hubcaps or wheels, though this is obviously less permanent.

Instructions for mod

See how to links in table below.

Materials to use for mod

- Pizza trays

- Metal sheet

- Coroplast

- Serving Tray

- Fiber glassing over hub caps

Different ways to attach to car:

Screw into rims, Drill and tap 3 holes equally spaced onto the rims, Screw disks onto rims using taped holes.

Use current hub caps (screw, glue)

Buy pop on moon disks

Buy screw in moon disks

Use lug nuts (drill into them and epoxy in nuts on the ends)

Buy OEM wheel covers and pop them into place

Disks can be painted before screwing onto wheel. A pattern can be painted / stencilled onto the disk which may help hide the mod

Note: Ensure that the disk is easily removable or a hole cut to allow access to the tyre valve for tyre pumping

Note: Aero OEM whell covers will allow acces to the valve stem

User experiences

Please enter your user name and any relevant data in the table

User data
User Name	Car Make, Model, Year	Cost of Mod	Time to Perform Mod	MPG Before Mod	MPG After Mod	MPG improvement	Instruction Link
Weather Spotter	Toyota, matrix, 2006	$4.5 a wheel	20 min each wheel	45.06	46.54	3.17% (1.48 MPG) ABA test data	Weather Spotters wheel cover how to
Concrete	S-10, 2000			28	29.3	4.6% (1.3 MPG) ABA test data	Smooth wheel discs tested A-B-A - 4.6% mpg improvement @ 65 mph
cons	04 Ranger	$20	1 hour	30	31.5	4.76% (1.5 MPG) tank to tank testing, previously no hubcaps, making mpg gains easier
Echo-Francis	Toyota Echo 2005	4$ a wheel	30 Min each wheel	58,3	59.6	2.15% (1.3 MPG) ABA test data (50 MPH Highway Test Results) Test Results	Echo-Francis Wheel Covers (Pizza Pans)
Oil Pan 4	1984 diesel suburban	$80/5hub caps	>5Min total	18.5	19.1	3% tank to tank testing, previously no hubcaps and while towing	Factory aero wheel covers just buy them cheap and install
Gealii	Pontiac Grand am 2002	$3usd	2 hours	27.09	28.41	1.3 mpg gain tank to tank	DIY coro covers

Problems / Consequences of mod

Any way you attach wheel covers, they might come off, if so you are liable for what they hit. On the other hand it seems perfectly acceptable, even expected for OEM or OE style wheel covers to fall off.

If you bolt them onto the rim you are removing some material from the rim and might weaken it.

You might unbalance you wheels with the cover causing tread wear, rough ride and suspension issues.

The covers may reduce access to the tyre valve used for pumping up the tyre

These may block air from flowing by the brakes, keeping them hotter.

With OEM wheel covers all these problems are addressed, they are attached very well and need no modification, they are balanced, they allow access to the valve stem and they have small gaps or slits to allow minimum air flow for brakes and hub cooling (the gaps can be covered with clear tape for long highway trips).