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Hardware update gained 15% range

24K views 69 replies 24 participants last post by  Reddo 
#1 ·
Did a hardware update today which will increase the range by almost 15%.
The update was done by FTTM(ferry to the mainland) and MTOTA(money transfer over the air)
Paid 950 euros for the update. I've only downloaded it to my garage and will install it to the car later. Wheel Tire Car Vehicle Window
 

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#2 ·
:)

Are you selling the 22's?
 
#5 ·
Every time I see the I-Pace with 18's it amazes me how it somehow makes an 18" wheel look so tiny. My current car has 16" wheels and even those don't look as small as 18"s on the I-Pace. I think it's the huge tyre sidewalls tricking the eye perhaps?

Do we know how it reduces the range so much having a bigger wheel? Presumably the rolling radius of both wheels and their respective tyres is roughly the same? I'd have thought the reduced flex in the smaller tyre vs the bigger tyre would help get more power to the road, or is it simply a case of the smaller wheel package being lighter?
 
#10 ·
sciencegeek said:
I think the most important parameter is the fact that there is much more mass further away from the axle, so a lot more energy is required to accelerate to the same radial speed. The wheel is probably also heavier overall.
18" 1022 with Mich Lat Tour 235/65 24,7 kilos
20" 5070 with GY Asymmetric 245/50 28,8 kilos
22" 5069 with Conti PC6 255/40 34,4 kilos

The tyres on 18 and 20 weighs the same. The difference is the rims.
 
#13 ·
FENorway said:
sciencegeek said:
I think the most important parameter is the fact that there is much more mass further away from the axle, so a lot more energy is required to accelerate to the same radial speed. The wheel is probably also heavier overall.
18" 1022 with Mich Lat Tour 235/65 24,7 kilos
20" 5070 with GY Asymmetric 245/50 28,8 kilos
22" 5069 with Conti PC6 255/40 34,4 kilos

The tyres on 18 and 20 weighs the same. The difference is the rims.
Wow that's a huge difference ... and much of that weight is further away from the axle ...
 
#15 ·
FENorway said:
Did a hardware update today which will increase the range by almost 15%.
The update was done by FTTM(ferry to the mainland) and MTOTA(money transfer over the air)
Paid 950 euros for the update. I've only downloaded it to my garage and will install it to the car later. 20190514_161712.jpg
The same wheels I have :)

I have ordered 20" for mine for the summer as range is so good anyway.

Not sure if I could have gone for 22" as I don't have air suspension.
 
#18 ·
BillCB said:
Skinny tyres have less rolling resistance. 22 inch wheels have fat tyres.
Do they? The main contributor to rolling resistance seems to be flexing of the sidewall as the tyre rolls along the road. The low profile tyres have much stiffer sidewalls and so flex less - hence the harsher ride. Sure they are wider, but is rolling resistance really greater?

Anyway, rolling resistance only makes up about 20% of the power loss. If the wider tyres add say 20% to the rolling resistance, that's only a 4% increase in overall losses.

And the 40kg weight penalty for the bigger wheels only represents less than 2% of the overall weight of the car.

So that makes 6% ...

That's why i believe some real world testing is needed.
 
#19 ·
I think the extra weight being at the end of the axel and not as a overall percentage may be the major contributing factor ( force mass and distance from force ) and they require more force to be rotated.

Google will probably explain it better.

Left my nerd had indoors today :)
 
#20 ·
It also depends on the distribution of weight across the diameter of the wheel - weight "further out" from the axle takes more force to rotate than the same weight closer to the axle. So you could have two wheels (including tyres) of the same overall diameter and the same weight, but the one with the weight distribution closer to its point of rotation will use less energy (not taking into account other factors such as rolling resistance and tyre wall flex)
 
#22 ·
smithy2167 said:
Well FENorway, before you swap the wheels, can you do some controlled tests of consumption in various conditions with the 22's. Then repeat the tests as closely as possible with the 18's.

I'm personally quite skeptical that there'll be anything like 15% difference.
I will try. But will not switch to 18" this week.
 
#23 ·
The 22" tyres have a 7% bigger contact patch than the 18s with the same loading applied.

In the UK the bigger tyres specified as OEM also have a lower efficiency rating ('stickier' compound = more grip - and more friction). I understand this is not the case in all markets though.
 
#24 ·
22" tyres in Norway are Conti PremiumContact. They have C im RR-rating. The 18" Michelin have A and are rated as Ultra Low Rolling Resistance ULRR-tyres.
I dont know the reason why JLR chose Conti over Pirelli. The Pirellis are better on both RR and noise.
 
#25 ·
There's a lot of incorrect pseudo science on this thread. Confusion between mass, inertia, weight, losses.
Heavier wheels will increase rolling resistance losses in direct proportion to the increased WEIGHT. A very small effect.
If the wheels have more of their mass distributed at a larger radius, that will increase their INERTIA. It will NOT in itself affect the rolling resistance losses or economy at a steady speed. It will slightly increase the ENERGY required to accelerate to a given speed, but also increase the energy regenerated. A tiny net increase in overall losses.
Fatter tyres will increase aero losses, but I doubt if the effect is significant. I may be wrong.
So, none of these factors explain the large observed difference in range.
I believe larger wheels with fatter, flatter tyres do have a higher RR, but I don't understand why. The physics (stiffer tyres) would suggest the opposite.
The larger/wider contact area will give greater scrubbing losses on cornering or if the wheels have toe-in. No idea how significant this might be.
But I suspect the dominant factor by far is the tyre compound. If, as FENorway reports, 22s have a C-rating and 18s have ULRR As, then I think that's the main factor.
Why have JLR done this? Probably to get the best "headline" figures for range based on ULRR rubber on 18s, while they assume anyone choosing 22s is more interested in handling/cornering than range.
 
#26 ·
My earlier post saying skinny tyres have less RR is apparently wrong, according to Mr. Google. Still, Jaguar's own figures clearly show they are more energy efficient.

My comment was based a book I bought many years ago, "Chilton's More Miles to the Gallon", where he advised "hypermilers" to install the thinnest tyres possible and pump'em up as high as possible. This was during the oil crisis in the 1970s and I guess the technology has changed a bit since then!
 
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