Wheels & Tires

[CheeseheadEarl]

I won't pretend to completely understand your calculations, Snick.

I do get the general theory you have though.

My question is do those calculations take into effect the fact that the Elio has 3/4 the rubber on the road as a car?

 

[AriLea]

I think we should consider, EM, having working relationship with a tire company, can have any tire they want, if it's production tooling still exists. I can currently buy 145x13's at Walmart.
I think at the volumes EM is stating, they will ramp up production on anything EM wants. I would expect they will put on the most inexpensive and light weight tire, So I'd say a 145 radial tire. For the loading factors involved nothing bigger is required. These are still modern, reliable, off the shelf tires.
Other venues will restock accordingly.

 

[Jim H]

I think we should consider, EM, having working relationship with a tire company, can have any tire they want, if it's production tooling still exists. I can currently buy 145x13's at Walmart..

If I'm not mistaken EM has a relationship with Cooper Tires as the tire provider. I'm sure they either have the appropriate tire or will develop one.

 

[wheaters]

I think we should consider, EM, having working relationship with a tire company, can have any tire they want, if it's production tooling still exists. I can currently buy 145x13's at Walmart.
I think at the volumes EM is stating, they will ramp up production on anything EM wants. I would expect they will put on the most inexpensive and light weight tire, So I'd say a 145 radial tire. For the loading factors involved nothing bigger is required. These are still modern, reliable, off the shelf tires.
Other venues will restock accordingly.

I would agree on a 145x13 which in my view would be a good compromise. I was taken to task by one poster who says these are far too wide and we should be thinking about 85 section tyres. As far as I can tell, these are moped tyres and I wouldn't want to drive any thing other than a moped on them, certainly not a vehicle capable of over 100 mph.

Purpose made tyres are expensive. I researched having some 145 x 16 radials made to suit my cars unusual wheel size. I found a company who could do it but I would need to have found about $60,000 as set up costs because the moulds don't exist. Despite Elio's optimistic high volume production numbers, if the vehicle needs a specially made tyre, they will always be expensive in the aftermarket supply chain.

 

[ArthurKent]

The idea is to allow a driver to continue to drive out of a bad neighbor hood or unsafe road to a repair station.
It adds a false sense of security.



I saw that post too. So that solves the tire rotation question. I wonder why. Over steer? Weight?

Handling is the obvious reason, since the sprung weight on the rear will be virtually the same as
that shouldered by the front tires. It may be that Elio engineers, in order to obtain the 84 MPG that they had
not yet achieved at last word (81.5 MPG as I recall) will narrow the rear wheel to reduce rolling resistance
and increase MPG. Personally I don't want a fat tire where there is snow or ice. especially on a single
rear wheel.

 

[ArthurKent]

If the Elio is to achieve its fuel economy goals, tires will have to be < 85mm average section width, give-or-take. For this vehicle, rolling resistance is greater than aerodynamic resistance for a 'mixed mode' and most highway driving cycles that most of us will use it for! Also, the tires will contribute to frontal area (adding aerodynamic form drag) and because airflow is so turbulent at exposed parts of tires it also increases the aerodynamic friction drag component.
My guesses:
15" diameters all around. Maybe 16" or larger for rear, probably not.
fronts: 85mm or 90mm section widths; recommended pressure range from 60-77psi depending on winter/summer.
rear: 90mm-105mm section width; recommended pressure range from 50-68 psi depending on winter/summer.
Also, I think the designers may have to compromise on aesthetics and fair all three tires all the way down to 1.5" off the ground. Otherwise that rear tire will add measurable form and friction drag, and car will struggle to achieve 84mpg at realistic freeway speeds, which is what drivers expect from claims, not to have to travel at 65mph top speed to get the 84mpg. I contend most people will expect to get 84mpg going 75-80 mph, which is substantially more challenging.

I would bet that the 84 MPG figure is based on the govt highway test cycle which is NOT anywhere near realistic Interstate speeds.
As I recall, the top speed in that test is a mere 53MPH and lasts about 12 minutes, with a coast down midway thru to around 30 MPH then an accelleration back to speed. Since the test does not involve constant speed, I cannot compare it to typical highway driving (sarcasm), but going from 55 to 80 MPH (constant speed) makes a HUGE difference in energy required. For example, accurate lab tests of the Tesla Model S show its driving range (consider this parallel to MPG) at 55 MPH to be 300 miles, and, under precisely the same driving conditions, drops to 200 miles at 80 MPH, or 33% less. The Tesla has the best aerodynamics
(CD) of any production vehicle.
The 81.5 MPG that was mentioned by the engineers (as of several weeks ago) obviously was calculated based upon the currently planned tire sizes that will be on the production vehicle (apparently 15 inch, acording to one comment). I find it hard to believe that any automaker would allow a portion of the body (fenders in this case) to come within 1.5 inches of the road surface or even extend below the ride height of the vehicle (claimed to be the same as the Mustang, or close to 5 inches). Those fenders wouldn't last very long at a height of less than 2 inches. In my case I'll be ordering the optional motorcycle fenders - I seldom drive at Interstate speeds and around town aero counts for very little - at moderate speeds, weight is the overwhelming MPG determinate. I want the
looks of allow wheels and don't care for the full fenders. They also need to eliminate the black color of the wheel access panels - the two tone scheme looks God-awful. It's OK to reduce costs but the effect should not create ugly vehicles. Paint those black panels body color. Would make a huge difference.

 

[lkptpete]

One option:

http://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=ContiEcoContact+EP

 

[lkptpete]

One option:

http://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=ContiEcoContact EP

145/65-15

 

[lkptpete]

145/65-15

Another one... Same size.

http://www.tirerack.com/tires/tires.jsp?tireMake=Dunlop&tireModel=Enasave+01+A/S

 

[karl]

Who should set the testing parameters for fuel mileage?
http://www.fueleconomy.gov/feg/how_tested.shtml
The oil companies?
http://www.epa.gov/fueleconomy/