Experiment: smooth wheel discs tested A-B-A - 4.6% mpg improvement @ 65 mph

[MetroMPG]

Daihatsu did, on their concept car:
Concept Car - Daihatsu UFE-II

[azraelswrd]

Hey guys,

For slip-on hubcaps (no restraining bolts), what is the safest way to take them off?

1) Pry from the outer edge with a screwdriver
2) Pull straight off with hands by holding spokes
3) Other

[Bror Jace]

I think it depends on the cover ... but I think the best way is to pry the edges (carefully) all the way around until the cover pops off.

Of course, with my new full moon covers, that's the only option I have.

Clear covers? I think they'd get dirty, scratched and pitted quickly ... then look very, very poor.

[tasdrouille]

If anyone still had doubts on that one...

[MetroMPG]

Great find, tas. What's the source?

[tasdrouille]

SAE paper 2007-01-1047 The Influence of Rotating Wheels on Total Road Load

[MetroMPG]

Those aftermarket rims are "air blenders"!

It's interesting to note that the exposed 19 inch rim is the worst case, but when masked, it's the 2nd best case - better than the masked 17 inch rim.

To me that suggests the shrinking gap between tire and wheel arch (you can see the progression in the photos) may be having a beneficial effect. And it may be even more significant if they didn't control for tire width as well (they apparently didn't control for overall circumference, so I'd be surprised if they did control for width).

[NeilBlanchard]

Hello Bror,

Originally Posted by Bror Jace

I am seriously considering buying these instead:

Full Moon Racing Disc Hubcaps, Stylish Look, Great Prices, AutoAmenity.com

These do not have valve stem holes -- do you have to use short stems that don't stick out, and you have to pull the cover to check the pressure and/or add air?

Or, could you drill a hole? Or, is there a company that sells these with the hole already there?

[Bror Jace]

Neil, I bought the 16" full moon discs and have had them on my car for about 6 weeks. I posted pics in the "Racing Discs, Are They Worth It?" thread.

I can't say I can discern any difference in mileage as the air temps around here have dropped about 15-20 degrees since August. This should have a larger, negative effect than the discs' positive one. As the air temps drop, my mileage follows. It's been this way with every car I've ever owned.

Anyway, mine are solid with no access holes to check tire pressures (there are places inside the cover (gaps in the 'teeth') for the valve stem but you have to remove them to check the pressure. However, I think this will take just a minute or so with a flat-head screwdriver.

Drilling through them should be possible as they are fairly thin metal ... but I would not advise it. I'm not sure the benefits outweigh the damage done to the not-exactly-cheap discs.

[aerohead]

Thanks Concrete! It is alot of work and I'm glad you weren't punished for your good deed!