8" wheels?

[J. Eastwood]

We're considering using these on this years car and was looking for opinions and info. So who uses 8" wheels? What do you like or dislike about them? Where can you find some? Thanks.

[J. Eastwood]

We're considering using these on this years car and was looking for opinions and info. So who uses 8" wheels? What do you like or dislike about them? Where can you find some? Thanks.

[exFSAE]

Why are you considering them? Not saying its a good or bad idea.

I'd pick a tire first.. and that should set your rim width recommendation.

And the important thing with "do you like them or not" should probably be more focused toward specific manufacturers. Keizer, Kodiak, Jongbloed, BBS, etc all make 13" wheels. Quality, price, and availability are all over the place.

[Drew Price]

I interpreted this at first as asking about 8" diameter wheels, like karting wheels, rather than 8" wide wheels, so I guess we need more clarification.

I briefly looked at 8" dia wheels due to the cost and availability, and from a rotational inertia perspective .... but it would just look so silly. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Best,
Drew

[mech5496]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Drew Price:
I briefly looked at 8" dia wheels due to the cost and availability, and from a rotational inertia perspective .... but it would just look so silly. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Best,
Drew </div></BLOCKQUOTE>

If I'm not mistaken,there was a car running 8" dia. rims in FSUK in 2006, and it looked...hmmm...weird! http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[Composites Guy]

Excellent... excellent idea!!!!!

I have been trying to persuade our team here for 4 years now to go to 8" wheels and my reasoning goes like this. Our car is very light (325-350lbs). Unless they day is a baking hot one in August, we do not see tire temps (10" hoosiers) above 130F and this is not up to the manufacture temperature recommendation. We see corner weights with 10" wheels that are approximately HALF that of our previous 13" wheeled cars. 8" wheels would allow us to reduce corner weights further, and perhaps increase tire temps. A similar arguement could probably be made about tire rotational intertia.

But... 8" wheels will introduce new difficulties. Coming up with packaging for a quality front brake setup will be a nightmare. Perhaps the brake will need to come outside the wheel (which adds weight). Perhaps the brake rotor mounts to a custom rim and the caliper rides inside it (towards the spindle). Then there's the difficulty of sourcing tires. I have found a tire manufacturer that has the molds 8" tires already (though harder compound) and that molds softer, larger tires. If we bought about $5000 dollars worth of tires they would be willing to custom mold us a soft compound 8" tire. Rims are no problem, as there are available commerical spun aluminum rims, or we could make carbon, or aluminum ones in house.

I encourage you to pursue it... but only if you are up the the challenge, well financed, and only if you are already building an ultralight car. Don't worry about your car looking silly... silly looking cars that go fast are genious!

[J. Eastwood]

Thanks for everyone's input so far. About 4 o'clock in the mornin I woke up and had some design ideas streaming through my head. So now after searching for tires I'm now considering 10" dia. rims instead of the 8"s I had in mind. I was hoping I could still get a set of Keizers but I'm not seein what I want on the website. So where can I find some good light 10"ers?

[Kirk Feldkamp]

http://www.hiperracingwheels.com/

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by J. Eastwood:
Thanks for everyone's input so far. About 4 o'clock in the mornin I woke up and had some design ideas streaming through my head. So now after searching for tires I'm now considering 10" dia. rims instead of the 8"s I had in mind. I was hoping I could still get a set of Keizers but I'm not seein what I want on the website. So where can I find some good light 10"ers? </div></BLOCKQUOTE>

Good and light do not necessarily go hand in hand.

[rjwoods77]

BALLLIIINNNNNN!!!!!

http://www.jackssmallengines.com/gokaz_whls8a.cfm

8" is a standard size for gokart wheels if i am not mistaken. I can see it now. Some British team will recreate the tyrrell six wheeler using kart tires. Nice!!!

http://en.wikipedia.org/wiki/Tyrrell_P34

[Drew Price]

Ooh, with Grade 5 hardware. And for an extra $1, you can upgrade from the '5/8" Standard Ball Bearings,' to the 'Precision' ball bearings.

I had the same thought about the Tyrrell, but then remembered rule 2.1. 4 wheels only.

I started looking at the 8" stuff because it is wicked cheap. Like, stupid cheap.

Best,
Drew

[rjwoods77]

Cant forget the March either.

http://en.wikipedia.org/wiki/March_2-4-0

[mjdavidson]

You must have been hanging out with Mark Ortiz.

[flavorPacket]

If you're going from 13s to 8s, I highly recommend stopping with 10s on the way down. 10s are NOT easy to work with. Packaging brakes, steering, a-arms is much easier said than done.

Furthermore, you're probably going to need to make custom calipers, and that takes a couple years of development before you can beat the OTS stuff.

[Drew Price]

I was thinking using a slightly inboard mounted rotor, either:

1) On the end of a live spindle, where you could get the diameter way down but keep it in the air stream to aid cooling, and make up for the reduction in thermal mass. Curse all the thermals going into the spindle and bearings though. And now you're probably bending the inboard end of the spindle in a different direction than the wheel. Or...

2) The mounting to the edge of the inboard rim half. I bet it could be set up to get more heat into the tires, for endurance anyways, and let you run a little harder compound for endurance. I bet the contribution during even two back to back Auto-X laps would not be very much.

You could tune the heat transfer with different thicknesses and materials of a phenolic gasket like mounting to the rim, and then float the caliper on the upright instead of floating the rotor. And like flavorPacket said, would need custom calipers, or some trick custom brackets. It would allow a nice big rotor diameter without the extra mass of a mounting hat and the inner non-swept area.

Best,
Drew

[Wesley]

To expound on the silly car statement, if it doesn't look good, nobody will buy it. Yeah, so we don't have to worry about that in competition.

But you do in engineering. Appearance can be as critical as design justification in a real market.

Not to mention with the new frame rules, it'll look like your car is wearing a rollerskate.