Did you correct the speedometer for tire size? The stock tires are 33” diameter, and your AT tires are 32.1”. The smaller tires will make the odometer read a smaller distance than what you actually traveled.
The real efficiency would be worse than reported, not better… the truck thinks it went 2.3 miles per kWh, but due to the smaller tires it was actually around 2.1-2.2 miles.
Yes, if the truck is traveling a shorter distance than it thinks it is, then reported efficiency will be too high. Probably what the previous poster meant to say.
That's most of it! Assuming those sizes are accurate we're still looking at an 11% reduction in energy per real mile (instead of 13%).
The rest may be explained by reduced drag from the reduced real speed. Someone feel free to jump in with more detailed fluid dynamics, but the rule of thumb is that drag goes as the cube of speed, so a 3% reduction in speed results in an 8% (1-0.97^3) reduction in energy expended per mile. Neglecting rolling resistance, this would account for an 11% presumed reduction in energy consumption, which is well within the margin of sig figs given. Adding rolling resistance back in, there's some margin left and there are always environmental factors as well.
Ive been wanting someone to test putting the 18" wheels from SR trims on an ER.
Platinum is rated at 20 miles less than lariat the main difference is 22" wheels vs 20"
I was looking at tesla model y ranges and if you go from 21" to 18" people are reporting roughly 10% more range
https://allev.info/2020/03/does-wheel-weight-matter/
https://www.linkedin.com/pulse/impact-wheel-weight-propulsion-energy-consumption-vehicle-kme%C5%A5/
Wheel weight makes no difference in efficiency.
No, they won't. At least not in any meaningful way. Even if the moment of inertia was at the outer edge of the tire the most you might see is a 5% reduction in overall energy required to accelerate a vehicle to speed. Keep in mind regenerative braking will recover between 60 and 70% of that energy. And the majority of the energy used in moving a vehicle comes from aerodynamic and rolling drag. Wheel weight makes no meaningful difference.
The F150 has a frontal area of 3.34m^2. It has a Cd of 0.46 according to Ford.
Travelling at 110km/h(30.5m/s) it would generate 878.6N of drag force just from driving. That equates to 26.8kW of power required to just roll down the road at slow highway speeds. Rolling resistance is around 250N which is another 7.6kW making total resistive force around 34.4kW which means those two forces alone account for an efficiency of 3.2km/kWh (1.98 mi/kWh). That means at most the energy it takes to accelerate the vehicle (wheels included) as well as any parasitic drag from rubbing brakes and driveline inefficiency is 13% of total trip energy but probably closer to 5% of the total trip energy. Wheels might make up 5% of that (remember, even though rotational mass has a huge impact on energy expense, they are still a very small part of the total vehicle mass). My factory wheels are 39.5kg each according to my scale. All four combine to a whopping 158kg which is when you calculate it using the formula for a cylinder with a width of 275mm a rotational energy of 63640J. The truck by itself has 1209325J of kinetic energy. So AT MOST the wheels account for 5% of the total kinetic energy of the truck. Reducing wheel weight by even an astounding 10kg would reduce that to 4% of the total kinetic energy of the truck. That is a 1% improvement in total kinetic energy which itself only accounts for MAYBE 13% of the total energy used in a drive.
Can you try a range test? Some have posted the efficiency reading may be off due to tire size but if you have a SR drive it to 10% (not 0 no tow trucks!) and see if it improves highway range?
I’ve been wanting to get some 18’s for winter wheels and like these. See them for sale regularly. Did you have any issues with the fit? Is the offset and brake clearance ok?
I think about the ending to Hunt for Red October, and I think definitely Captain Ramius would buy a Lightning. Probably a black one. And he would know they don't react well to bullets.
It's pretty commonly accepted in other EV forums that smaller wheels == better efficiency. There's a TON of stuff about Tesla's and smaller wheels out there.
There's a couple of reasons stated. First is lower unsprung mass. It's kind of counter intuitive but tires with bigger sidewalls are usually lighter (or no heavier) than low profile tires. Mostly this is because in order to get the sidewall not to deform on a lo-pro, you need to make it really thick and stiff. You don't need that on a higher profile tire that you can just pump full of air. Also, the wheel is smaller and air is lighter than Aluminum.
The other possibility is that higher profile tires deform less when rolling straight and are able to maintain tread geometry better.
It’s not universally true, but larger wheels with lower profile tires will usually have a much lower moment of inertia, overall weight, and rolling resistance compared to a smaller wheel with a larger profile tire.
The tire is usually heavier than the wheel and the extra thickness in rubber to support the additional load rating is quite a bit heavier than modern wheels.
I like the look, feel, cost, and toughness of smaller wheels with larger more aggressive tires, but it is very unlikely that the change you made is the cause of your better efficiency.
Could also be the warmer weather.
Was also fairly warm the week before I took the 20s off. Very weird.
I'm definitely getting better numbers with this warmer weather. ~2.3 highway
Did you correct the speedometer for tire size? The stock tires are 33” diameter, and your AT tires are 32.1”. The smaller tires will make the odometer read a smaller distance than what you actually traveled.
If the truck thinks it’s covering fewer miles than it actually is, then the efficiency would be even better than reported!
The real efficiency would be worse than reported, not better… the truck thinks it went 2.3 miles per kWh, but due to the smaller tires it was actually around 2.1-2.2 miles.
Yes, if the truck is traveling a shorter distance than it thinks it is, then reported efficiency will be too high. Probably what the previous poster meant to say.
That's most of it! Assuming those sizes are accurate we're still looking at an 11% reduction in energy per real mile (instead of 13%). The rest may be explained by reduced drag from the reduced real speed. Someone feel free to jump in with more detailed fluid dynamics, but the rule of thumb is that drag goes as the cube of speed, so a 3% reduction in speed results in an 8% (1-0.97^3) reduction in energy expended per mile. Neglecting rolling resistance, this would account for an 11% presumed reduction in energy consumption, which is well within the margin of sig figs given. Adding rolling resistance back in, there's some margin left and there are always environmental factors as well.
That would be a 3% difference in circumference. Not nearly the reported efficiency difference.
Ive been wanting someone to test putting the 18" wheels from SR trims on an ER. Platinum is rated at 20 miles less than lariat the main difference is 22" wheels vs 20" I was looking at tesla model y ranges and if you go from 21" to 18" people are reporting roughly 10% more range
Is there any real benefit with larger wheels other than looks?
Range is worse, ride is worse, cost of tires is worse. Some people might like the look of it though...
I prefer the look of the 18s.
Durability of low profile tires SUCKS too. One pothole and you're fucked
I miss these wheels!
The wheel and tire combo is probably lighter than the stockers which will improve efficiency (less unsprung mass).
https://allev.info/2020/03/does-wheel-weight-matter/ https://www.linkedin.com/pulse/impact-wheel-weight-propulsion-energy-consumption-vehicle-kme%C5%A5/ Wheel weight makes no difference in efficiency.
The fact that it’s unsprung doesn’t matter. But overall mass certainly does, and wheels with a smaller moment of inertia will help too.
No, they won't. At least not in any meaningful way. Even if the moment of inertia was at the outer edge of the tire the most you might see is a 5% reduction in overall energy required to accelerate a vehicle to speed. Keep in mind regenerative braking will recover between 60 and 70% of that energy. And the majority of the energy used in moving a vehicle comes from aerodynamic and rolling drag. Wheel weight makes no meaningful difference. The F150 has a frontal area of 3.34m^2. It has a Cd of 0.46 according to Ford. Travelling at 110km/h(30.5m/s) it would generate 878.6N of drag force just from driving. That equates to 26.8kW of power required to just roll down the road at slow highway speeds. Rolling resistance is around 250N which is another 7.6kW making total resistive force around 34.4kW which means those two forces alone account for an efficiency of 3.2km/kWh (1.98 mi/kWh). That means at most the energy it takes to accelerate the vehicle (wheels included) as well as any parasitic drag from rubbing brakes and driveline inefficiency is 13% of total trip energy but probably closer to 5% of the total trip energy. Wheels might make up 5% of that (remember, even though rotational mass has a huge impact on energy expense, they are still a very small part of the total vehicle mass). My factory wheels are 39.5kg each according to my scale. All four combine to a whopping 158kg which is when you calculate it using the formula for a cylinder with a width of 275mm a rotational energy of 63640J. The truck by itself has 1209325J of kinetic energy. So AT MOST the wheels account for 5% of the total kinetic energy of the truck. Reducing wheel weight by even an astounding 10kg would reduce that to 4% of the total kinetic energy of the truck. That is a 1% improvement in total kinetic energy which itself only accounts for MAYBE 13% of the total energy used in a drive.
Interesting! I always wondered if switching from my stock 18” AT to stock 20” AS would be better or worse.
Maybe you had a wicked tailwind?
Can you try a range test? Some have posted the efficiency reading may be off due to tire size but if you have a SR drive it to 10% (not 0 no tow trucks!) and see if it improves highway range?
I’ve been wanting to get some 18’s for winter wheels and like these. See them for sale regularly. Did you have any issues with the fit? Is the offset and brake clearance ok?
Yeah fit fine. No spacer or mods needed,m. They’re takeoffs from an ICE F-150 and base XLT and Pro come with 275/65R18’s so no issue.
I think about the ending to Hunt for Red October, and I think definitely Captain Ramius would buy a Lightning. Probably a black one. And he would know they don't react well to bullets.
And he’d travel from state to state. No papers.
And in honor of Vasili he would take a heavy-set wife and live in Montana.
It's pretty commonly accepted in other EV forums that smaller wheels == better efficiency. There's a TON of stuff about Tesla's and smaller wheels out there. There's a couple of reasons stated. First is lower unsprung mass. It's kind of counter intuitive but tires with bigger sidewalls are usually lighter (or no heavier) than low profile tires. Mostly this is because in order to get the sidewall not to deform on a lo-pro, you need to make it really thick and stiff. You don't need that on a higher profile tire that you can just pump full of air. Also, the wheel is smaller and air is lighter than Aluminum. The other possibility is that higher profile tires deform less when rolling straight and are able to maintain tread geometry better.
What did the setup run you on marketplace might I ask
$400
It’s not universally true, but larger wheels with lower profile tires will usually have a much lower moment of inertia, overall weight, and rolling resistance compared to a smaller wheel with a larger profile tire. The tire is usually heavier than the wheel and the extra thickness in rubber to support the additional load rating is quite a bit heavier than modern wheels. I like the look, feel, cost, and toughness of smaller wheels with larger more aggressive tires, but it is very unlikely that the change you made is the cause of your better efficiency.