Airless Tires - Lower Rolling Resistance & Lower Maintenance?
 

As I took a moment to take a second look at this picture of the MIT ' Hiriko' folding urban EV:

http://i146.photobucket.com/albums/r.../bubblecar.jpg

I did a double take on the wheels. They look to be earth-going versions of the Lunar Rover wheels? And they are similar to the ERW (Energy Return Wheel).

If their aerodynamic openness would need a solution, but they have two things that would be very good for a high efficiency car: lower rolling resistance than conventional wheels (the ERW claims 50% improvement) and they would not require inflation checks; which are more difficult when they are enclosed in low drag body work. And they can't blowout.

first thing I thought when I saw those is that they might get full of debris and need to be cleaned out constantly to stay balanced :confused: a rock in one of those openings would make for a really wobbly ride!

...no worse than current "snow" tires I'd guess.

How often do you get big rocks in an urban enviornment, though?

I could see some jokers stuffing garbage between the spokes, though.

Well, if the spaces were filled in with a strong fabric, that would solve both the aerodynamic drag and the sand/gravel/schmeg problems at the same time?

Normal pneumatic tyres can be run at higher pressure to compensate for increased load, even between the front and rear of the car.

Can these compensate for increased load?
If not, how are these practical for everyday use where you might drive alone, or with four passengers, on the same day.

In the same vein, would each model car only use a tyre made for that car?
What happens if I want to run wider or taller tyres, or maybe I'd want to run fancy mags.

I think these are a great concept, but like many concept cars, maybe it's just not practical.

... or am I missing something? :confused:

probably work great and cost the same , guessing not good for heavy vehicles .

Let me add another important possibility - and that is tunable suspension. It is likely (though possibly not) true that low rolling resistance means a stiff tire, with the only large scale flexing being for the purpose of keeping a good contact patch on the road - but the tire ideally would probably not act like conventional pneumatic ones.

So, already the requirements on the suspension are different: a pneumatic tire absorbs about half of all the bumps - all the small ones - while an über-low rolling resistance tire *probably* would not. The suspension would then have to be much more compliant in the first small part of the motion, and then it would have to be progressively less compliant and higher compression dampening and spring rates.

So, these together would be roughly the same with heavier loads - the über-low rolling resistance tire already would be similar to a higher pressure pneumatic tire. And since the suspension would be the area that would be most affected by heavier loads with either kind of tire, I don't think this is something we need to particularly worry about.

The suspension *does* need to be considered for both ride height and level attitude, when the vehicle is a low aerodynamic drag. If a heavy load is put in the vehicle, the ride height and/or the normal angle of the body will be affected - so the suspension on a low aerodynamic drag vehicle would ideally be able to level itself and compensate for load changes. And this would have the ability to work correctly with very low rolling resistance tires, along with a low aero drag bodies.

Thanks Neil.
You're right of course, I feel silly now. :o

I remember, now, when our locally produced GMH vehicles went from cross ply tyres to radial tyres.
Their marketing people made a big deal about their new "Radial Tuned Suspension".

High end performance cars already feature suspension that's adjustable on the move, something similar could certainly be used in conjunction with these tyres.

They look like Michelin's Tweel :

Michelin Tweel - The Airless Tire