Quote:
Originally Posted by Vekke
I have been cracking some numbers related to my new wheels and tires and it seems that 50% of your electric cars energy consumption comes from wheels and tires. So saving potential is huge.
It is not wise to put 255/45R19 tires to your family car if your goal is to maximize the range. I have already proven that there is easily 10% savings potential in Model Y, but more accurate estimation suggest 12-15% savings when everything is done rigth.
Some manufacturers are running wiser tire sizes than others. but there is more to this than just tire size as aerodynamics are so important. I have seen good trends like in BMW IX1 205/65R17 size when taking measurements, also 205/55R19 from goodyear used in Renault looked very aerodynamic, but those I havent yet measured.
My plan is to prove you can have good driving characteristics even with tall and narrow tires. |
If one does the Road Load calculations for 'ANY' car, whether Otto-cycle, Diesel-cycle, Otto-Hybrid, Diesel-hybrid, ditto Plug-in hybrids, or BEV, they'll find that, at some thermally-equilibrated, constant-speed velocity, that the aero and R-R are equal to one another ( 50% each ).
* The 1924 Rumpler Tropenwagen Limousine's wheel addition to it's basic boat-hull body is credited with an approximate 50% drag increase by Rolf Buchheim of VW, who did the wind tunnel testing.
* The 1981 VW-Flow Body long-tail, also by Buchheim, is credited with a 53.5% drag increase over it's basic body.
* The 2012 Audi A3 Hatchback demonstrated a 47.66% drag increase with the addition of wheels.
Adding full, front and rear wheel skirts reduced the wheel drag increase to only 37.38%. Adding full-swept wheel fairings, as with the VW XL1, would reduce the balance of the wheel drag by up to 70%, according to Goro Tamai of MIT.
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* The dynamic R-R fraction varies linearly with increased velocity.
* The dynamic aero fraction of wheel drag varies geometrically, at v-squared for 'force', and v-cubed for 'power.'
* The wheel's 'windage' / 'ventilation' drag portion can be 'zero-to-3% at top speed ( 141-mph [ 227-km/h ] on the TESLA Model 3, depending on wheel cover design.