QUESTION 2023 Air Touring Tire efficiency

[marcusclarke]

Hello everyone,
I'm a new owner and new to this forum.
Why is the range of the Air Touring 19" option rated so much higher (~411mi) than the 21" Aero Blades (~367mi) ? Is it due to the aerodynamics of the rim, the tire compound, or something else? I need to get something to replace my 21" Aero Blades during winter. With temps near freezing, my weekly 213 mi commute from Albuquerque, NM to Greer, AZ barely has 5% left after a 100% start - and that's driving at the speed limit. What's weird is that I have no issue going the other way (3.5mi/kWh vs. 2.5mi/kWh). Now there is a 3,000' elevation gain, East->West, but I don't think it makes that much difference.

Any thoughts, comments, or suggestions would be most welcome.

Thanks in advance....

Marcus

 

[Cosmo Cruz]

Has to do with tire size and this makes sense if you think about it.
The 19" tire has a shorter distance to travel... three inches fewer than the 21" tire.

 

[Adnillien]

Hello everyone,
I'm a new owner and new to this forum.
Why is the range of the Air Touring 19" option rated so much higher (~411mi) than the 21" Aero Blades (~367mi) ? Is it due to the aerodynamics of the rim, the tire compound, or something else? I need to get something to replace my 21" Aero Blades during winter. With temps near freezing, my weekly 213 mi commute from Albuquerque, NM to Greer, AZ barely has 5% left after a 100% start - and that's driving at the speed limit. What's weird is that I have no issue going the other way (3.5mi/kWh vs. 2.5mi/kWh). Now there is a 3,000' elevation gain, East->West, but I don't think it makes that much difference.

Any thoughts, comments, or suggestions would be most welcome.

Thanks in advance....

Marcus

3000 foot elevation gain requires 6.1 kWhr of additional energy assuming 100% efficiency which is not case. Going the other way you gain that 6.1 kWhr back. For your touring this is over 6.5% SOC. I would expect a 13% difference between the two directions.

 

[Neurio]

Hello everyone,
I'm a new owner and new to this forum.
Why is the range of the Air Touring 19" option rated so much higher (~411mi) than the 21" Aero Blades (~367mi) ? Is it due to the aerodynamics of the rim, the tire compound, or something else? I need to get something to replace my 21" Aero Blades during winter. With temps near freezing, my weekly 213 mi commute from Albuquerque, NM to Greer, AZ barely has 5% left after a 100% start - and that's driving at the speed limit. What's weird is that I have no issue going the other way (3.5mi/kWh vs. 2.5mi/kWh). Now there is a 3,000' elevation gain, East->West, but I don't think it makes that much difference.

Any thoughts, comments, or suggestions would be most welcome.

Thanks in advance....

Marcus

Welcome Marcus. There are multiple factors making up the range difference difference between the 19s and 21s. The biggest reason is that the 21s are summer tires, which are stickier and therefore less efficient. Additionally, the 21s are wider tires and more road contact surface equals less efficiency. The elevation gain does make a huge difference.

Of note, you shouldn't be driving summer tires in weather under 45 degrees because the tire compound can develop cracks and break, making it potentially dangerous to drive on. I'd highly recommend all season tires or winter tires if you regularly drive in cold temps. The 21s don't have good options for this, so the 19s are a good alternative.

 

[GMan]

3000 foot elevation gain requires 6.1 kWhr of additional energy assuming 100% efficiency which is not case. Going the other way you gain that 6.1 kWhr back. For your touring this is over 6.5% SOC. I would expect a 13% difference between the two directions.

What's the formula to calculate kWhr versus elevation? It's it a simple rule of thumb (2 kWhr per 1000 ft), or more complex for example including weight, etc?

It would be good for me to know given my location and most road trips involve at least 2k feet elevation (to CA, AZ, or UT)

 

[marcusclarke]

Has to do with tire size and this makes sense if you think about it.
The 19" tire has a shorter distance to travel... three inches fewer than the 21" tire.

Thank you Cosmo.

 

[marcusclarke]

3000 foot elevation gain requires 6.1 kWhr of additional energy assuming 100% efficiency which is not case. Going the other way you gain that 6.1 kWhr back. For your touring this is over 6.5% SOC. I would expect a 13% difference between the two directions.

That's more of an impact than I thought and 6.5% is very significant when I'm in the single digits. Thank you!

 

[marcusclarke]

Welcome Marcus. There are multiple factors making up the range difference difference between the 19s and 21s. The biggest reason is that the 21s are summer tires, which are stickier and therefore less efficient. Additionally, the 21s are wider tires and more road contact surface equals less efficiency. The elevation gain does make a huge difference.

Of note, you shouldn't be driving summer tires in weather under 45 degrees because the tire compound can develop cracks and break, making it potentially dangerous to drive on. I'd highly recommend all season tires or winter tires if you regularly drive in cold temps. The 21s don't have good options for this, so the 19s are a good alternative.

Thank you Neurio. Indeed, I just found out that my tires are quite unsuited to my winter needs and absolutely plan to make the switch when I get back to Albuquerque. As a matter of interest, I have a set of 19" OEM rims from my previous 2020 Model S which appear to have identical fitment. I'll ask the tire pros if they might fit but it might invalidate the Lucid warranty. Are there any options other than the Lucid OEM 19" rims?

Thanks for your help,
Marcus

 

[xponents]

Thank you Neurio. Indeed, I just found out that my tires are quite unsuited to my winter needs and absolutely plan to make the switch when I get back to Albuquerque. As a matter of interest, I have a set of 19" OEM rims from my previous 2020 Model S which appear to have identical fitment. I'll ask the tire pros if they might fit but it might invalidate the Lucid warranty. Are there any options other than the Lucid OEM 19" rims?

Thanks for your help,
Marcus

It shouldnt invalidate the warranty! And they will fit, they are the exact same specs!

You could look into using the New Aero wheels that are on this forum and made by a forum supporter, but basically any rim with the same specs would work, if you want an more exotic rim.

 

[CoasterNerd]

Has to do with tire size and this makes sense if you think about it.
The 19" tire has a shorter distance to travel... three inches fewer than the 21" tire.

The circumference of the wheel has almost nothing to do with the reduced range of the 20" and 21" wheel vs. the 19" wheel. The tire circumference is about the same on all the wheels offered by Lucid (the smaller wheels have taller profile tires mounted to them resulting in about the same tire circumference on all three). The impactful differences have more to with wheel width and which tires are installed on each. The 20" and 21" wheels have higher rolling resistance summer tires. Also the 20" and 21" wheels have wider tires mounted to them which is detrimental to aerodynamics.

 

[Adnillien]

What's the formula to calculate kWhr versus elevation? It's it a simple rule of thumb (2 kWhr per 1000 ft), or more complex for example including weight, etc?

It would be good for me to know given my location and most road trips involve at least 2k feet elevation (to CA, AZ, or UT)

The formula is just the potential energy of the mass of the car raised by the elevation gain. It is linear with elevation so 2kWhr per 1000 feet is a good rule of thumb.

 

[CoasterNerd]

The circumference of the wheel has almost nothing to do with the reduced range of the 20" and 21" wheel vs. the 19" wheel. The tire circumference is about the same on all the wheels offered by Lucid (the smaller wheels have taller profile tires mounted to them resulting in about the same tire circumference on all three). The impactful differences have more to with wheel width and which tires are installed on each. The 20" and 21" wheels have higher rolling resistance summer tires. Also the 20" and 21" wheels have wider tires mounted to them which is detrimental to aerodynamics.

Oh, and wheel weight has an impact as well. The bigger wheels are slightly heavier. Plus the wider tires are likely a little heavier too.

 

[Steveinarizona]

Hello everyone,
I'm a new owner and new to this forum.
Why is the range of the Air Touring 19" option rated so much higher (~411mi) than the 21" Aero Blades (~367mi) ? Is it due to the aerodynamics of the rim, the tire compound, or something else? I need to get something to replace my 21" Aero Blades during winter. With temps near freezing, my weekly 213 mi commute from Albuquerque, NM to Greer, AZ barely has 5% left after a 100% start - and that's driving at the speed limit. What's weird is that I have no issue going the other way (3.5mi/kWh vs. 2.5mi/kWh). Now there is a 3,000' elevation gain, East->West, but I don't think it makes that much difference.

Any thoughts, comments, or suggestions would be most welcome.

Thanks in advance....

Marcus

Elevation makes a huge difference. I routinely drive from my house at 1440 feet above sea level to a golf resort at about 1280 feet above sea level. I drive like I don't care about range (and I don't). Going to the resort I get about 4 mkh and coming back about 3 mkh. I drive in the same manner both ways.

 

[Bunnylebowski]

Yeah the elevation problem affects all EVs, but the heavier the vehicle the more mass thus more power required to move it. This is why the Lucid doesn’t do so good in highway range tests which use more than one loop because just getting off an exit and then getting the car back up to highway speed kills efficiency, even on a pretty flat surface. Tom Moloughney’s 500 mile dream edition range test benefited from fewer exits and entries (I think his had 4, Kyle’s GT test had like 7-8), very little elevation change, no wind and perfect temperatures. Any one of those conditions not being optimal (also cold tire pressure) will dramatically impact efficiency.

 

[Daniel2022AT]

Has to do with tire size and this makes sense if you think about it.
The 19" tire has a shorter distance to travel... three inches fewer than the 21" tire.

This is not true. The overall circumstance of the tire is approx the same. A larger wheel is fitted with a tire with a shorter sidewall.

Larger wheels are much heavier and the extra rotational mass decreases efficiency.

Also, summer tires are designed to deliver better grip which means more friction with the road surface and less efficiency.

 

[ahmadr]

If you look at the detailed EPA consumption numbers, the highway rating difference is a mix of rolling resistance and aero, while the city rating difference is mainly due to rolling resistance differences between tires / wheels.

The impact of wheel/tire mass on consumption is negligible, as most of the additional stored energy is recouped through regenerative braking and not wasted.

 

[marcusclarke]

It shouldnt invalidate the warranty! And they will fit, they are the exact same specs!

You could look into using the New Aero wheels that are on this forum and made by a forum supporter, but basically any rim with the same specs would work, if you want an more exotic rim.

Very helpful. Thanks!

 

[Cosmo Cruz]

This is not true.

"Any thoughts, comments, or suggestions would be most welcome."

I think the OP just wants to chat. That's why I came up with my joke answer.

His question is (unworthy of a serious response ).

Or are we to assume there are Lucid owners who do not know that rolling resistance, wind, temperature, elevation change, weight, and speed all effect range? A lot?

 

[marcusclarke]

"Any thoughts, comments, or suggestions would be most welcome."

I think the OP just wants to chat. That's why I came up with my joke answer.

His question is (unworthy of a serious response ).

Or are we to assume there are Lucid owners who do not know that rolling resistance, wind, temperature, elevation change, weight, and speed all effect range? A lot?

Cosmo, I am a new owner and am aware of some of the variables you cite , but not all. I invited those who know more to help me understand better and indeed that has been the effect. I want to thank everyone who responded in good faith, as I believe my question was worthy of a serious response, even if you personally disagree.

 

[borski]

Play nice, kids. Don't make me turn this car around...