Wheels & Tires

[Marshall]

why? can we just call a truce?

Perhaps just agree it's not worth the cost and hope the cost goes down.

 

[Coss]

If we all agreed on everything there would be no reason to have these discussions. You don't learn anything new from someone who always agrees with you.

I can agree; it just felt like it was getting a little heated, and wanted to turn the temp down a little; never said stop.

Correct,
The best way to improve MPG is through aerodynamics.
The minuscule weight savings (both static and rotational) combined with questionable aerodynamics would be a minimal advantage.
Even with weight savings, it would only improve acceleration, which would only help city mileage which most consumers completely ignore.

Total weight savings would net 5-10lb at best.

In addition, the different driving characteristics of a carbon fiber wheel would require suspension tuning to compensate for the different rigidity of the CF wheels.

Besides the wheels; was the plan to reuse the stock tires? Or go with something a little more in style with the wheels? There's another $1K in the tires; plus those special wheels probably need some type of special mounting tools; and a way to balance them; so there's another cost to consider.

And if you've ever driven a car with low profile tires, you know how the ride changes. It will handle better, but it feels like you've taken the springs and shocks off and put in wood blocks. Potholes really become an issue then.
I would have to think those wheels are more for show than go.

 

[btg]

If we all agreed on everything there would be no reason to have these discussions. You don't learn anything new from someone who always agrees with you.

That is a great statement. That is as good as

"You can never make something cheaper by making it more complex. If you design something as simple as possible and it doesn't work you can always make it more complex to get it to work but you can never make it cheaper by making it more complex." ---Burt Rutan

 

[ehwatt]

That is a great statement. That is as good as

"You can never make something cheaper by making it more complex. If you design something as simple as possible and it doesn't work you can always make it more complex to get it to work but you can never make it cheaper by making it more complex." ---Burt Rutan

Burt is a great guy. He's my hero.

 

[Grumpy Cat]

If we all agreed on everything there would be no reason to have these discussions. You don't learn anything new from someone who always agrees with you.

I don't agree with that.

 

[CrimsonEclipse]

I can agree; it just felt like it was getting a little heated, and wanted to turn the temp down a little; never said stop.

Besides the wheels; was the plan to reuse the stock tires? Or go with something a little more in style with the wheels? There's another $1K in the tires; plus those special wheels probably need some type of special mounting tools; and a way to balance them; so there's another cost to consider.

And if you've ever driven a car with low profile tires, you know how the ride changes. It will handle better, but it feels like you've taken the springs and shocks off and put in wood blocks. Potholes really become an issue then.
I would have to think those wheels are more for show than go.

Oh man, I didn't even think about that.
Some sort of rim protector might be needed where the mounting machine grips the rim and maybe a steel insert around the bead edges.
I suppose sticky weights would work but the edge weights would likely be out of the question.

Carbon fiber is also very force specific. Depending on the thread materials, thread weave, epoxy, temperature, curing and injection technique, it will take certain forces but not others.

A design that takes compression and tension might fail with a twisting or shear force.

I remember the steep learning curve in the bicycle industry when they started making carbon fiber frames, handle bars, seat posts and wheels. The failures were interesting. The aviation industry had a more extreme learning curve. Beech basically put themselves out of business twice with failed CF designs... and then there's Boeing. (i could write volumes about this one)

Cf can be really strong but it comes with caveats. Failure mode is interesting. An over stress may not be visible or easily detectable and a CF structural failure is pretty sudden.

(ponders even more)

Yeah..... I'll stick with proven steel rims.

(Several ponders later)

and torque@! CF doesn't like clamping forces or rubbing forces. and over or under torque on the lug nuts would be a problem... (metal inserts?) and where the wheel contacts the rotor (more inserts?)

....and ... and.... and.... (breathes from oxygen bottle)

 

[Ty]

Oh man, I didn't even think about that.
Some sort of rim protector might be needed where the mounting machine grips the rim and maybe a steel insert around the bead edges.
I suppose sticky weights would work but the edge weights would likely be out of the question.

Carbon fiber is also very force specific. Depending on the thread materials, thread weave, epoxy, temperature, curing and injection technique, it will take certain forces but not others.

A design that takes compression and tension might fail with a twisting or shear force.

I remember the steep learning curve in the bicycle industry when they started making carbon fiber frames, handle bars, seat posts and wheels. The failures were interesting. The aviation industry had a more extreme learning curve. Beech basically put themselves out of business twice with failed CF designs... and then there's Boeing. (i could write volumes about this one)

Cf can be really strong but it comes with caveats. Failure mode is interesting. An over stress may not be visible or easily detectable and a CF structural failure is pretty sudden.

(ponders even more)

Yeah..... I'll stick with proven steel rims.

(Several ponders later)

and torque@! CF doesn't like clamping forces or rubbing forces. and over or under torque on the lug nuts would be a problem... (metal inserts?) and where the wheel contacts the rotor (more inserts?)

....and ... and.... and.... (breathes from oxygen bottle)

Before jumping on the carbon fiber bandwagon, how much weight savings could there even be? Even a stamped steel wheel as small as the Elios can't weigh much. How about time proven aluminum? Those probably don't weigh much at all. Yeah, I know: every unsprung ounce matters. But, how much?

 

[Marshall]

I don't agree with that.

I see what you did there.

 

[wizard of ahs]

I don't agree with that.

 

[CrimsonEclipse]

Before jumping on the carbon fiber bandwagon, how much weight savings could there even be? Even a stamped steel wheel as small as the Elios can't weigh much. How about time proven aluminum? Those probably don't weigh much at all. Yeah, I know: every unsprung ounce matters. But, how much?

From the few examples I've seen, a muscle car with rather large rims would save 10-15 lb per wheel or 40-60 lb for the whole vehicle. (normally the rims for those vehicles run around 60-65lb

So I'll go out on a limb and say an even 33% weight saving for the wheel (just for conversation sake)
I'm guessing the Elio wheels are about 15lb per wheel (assuming steel) so keeping the 33% reduction. 5 lb per wheel means a total weight savings of 15lb.