FullyGrounded

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Tires will do many things... smaller will have to work harder, but also is more efficient. But, smaller also falls into holes, crevices, and worse. Larger, while often less efficient; with EV, less so as EV doesn't have to pic up RPM to equate to power - 100% torque begins at go, unlike ICE vehicles. So, do as you must, as I will. haha
 

Crissa

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I do get 260 on my X in Virginia in the winter but up in Quebec during the summer it is more like 285 (in direct conflict with the assurances that I have been given that I'll lose 20- 30% of my range in cold weather).
No it doesn't. What is your average speed and distance travel in your Quebec trip vs your Virginia one? This is why the nxt garage guy took down his average speed.

A 20% weight reduction in tires will mean a total of 40 pounds in at least a 5,000 pounds vehicle. That is 0.8% difference. That will not impact rolling resistance in any significant way...
That's not the largest part of how weight of the tire will impact rolling resistance. A heavier tire takes more energy to flex; and it's unsprung weight, so it deforms itself more because its own weight is dynamic while the sprung load acts more static.

Like I said, it's complicated.

-Crissa
 
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OneLapper

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Here is some advice. Don't reference marketing materials as your evidence. A 20% weight reduction in tires will mean a total of 40 pounds in at least a 5,000 pounds vehicle. That is 0.8% difference. That will not impact rolling resistance in any significant way.

Tire pressure has zero to do with suspension setup. It has only to do with the total weight of the vehicle. You want to match the weight of the vehicle to the tire pressure so you get the optimum footprint with the best traction to fuel economy ratio. You increase the pressure above this, you will get better efficiency but with increased center tread wear. You decrease the pressure below this and you get better traction with increased side thread wear.

The max tire pressure of a Wrangler tire with Kevlar is 80psi. Same max pressure as without kevlar.

Pickup trucks may have lower recommended tire pressures because they have wider tires which provides a larger surface area for which that pressure to be applied. This is why a very heavy monster truck with huge tires only needs 10psi, but a bicycle with skinny tires might need 100psi+. But as you increase the load on the truck, you increase the tire pressure to increase a consistent footprint of the tread on the surface.

Hi CJ

I had to speak up on this one. Not criticizing you or anyone.

Tire pressure has everything to due with suspension setup. I race motorcycles and for many years raced Porsche 911s. I manage a fleet of tractor trailers and motor coaches. I spend $60k/yr on tires. Let me tell you, getting the right tire pressure is down right a science, and suspension is only one part of the equation.

For every vehicle, the tire is integral to the suspension. It's a major component of the suspension. Some will even go so far to say the tire is the most important part of the suspension. The tire absorbs impacts, conforms to the road, provides all the traction, and on and on. The air pressure is critical to all of this, and it varies by vehicle, tire, and function.

The suspension on my race car was developed around a specific tire at 42 psi (rear tires, and everyone knows a 911 will kill you fast if you don't know how to drive it with the throttle, so air pressure is critical to handling). I run Tubliss bladders on my enduro dirt bikes so I can run 0 psi if I need more traction. The Prevost motor coaches have 105 front axle, 110 drives, 85psi on the tag axle. The 53' tri axle trailers are 125 psi. The dual axle trailers have CTIS at 110 psi.

In general, a wider tire needs more air pressure to provide a consistent contact patch. But, to your point, some tires (say a Galaxy turf tire which I use to sell) are set around 3-5 psi.

Yes, tire pressure can be adjusted for different traction as conditions dictate.

Let just all agree that tire pressures, in general, have no "absolutes". Hell, even the engineers that design tires can't agree on what the "correct" tire pressures are supposed to be. Spring rate, shock absorbers (and DON'T get me started on shocks, that's even more complicated than tire pressures), vehicle weight, suspension geometry, etc etc are all factors that directly act on the tire, thus dictate tire pressure.

Air pressure just happens to be the one thing that the common person can change. That critical air pressure will vary by tire brand, composition, size, vehicle, road surface, temps, maybe even the position of the moon. Pretty sure on the moon part.

I'll spend some time on tires when we start seeing the CTs drop. The overall efficiency of the CT will vary greatly with tires (and tire pressures).

And we haven't even touched on filling tires with nitrogen!!!

I'm out. Off to find another cup of coffee.
 
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FutureBoy

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And we haven't even touched on filling tires with nitrogen!!!

I'm out. Off to find another cup of coffee.
You didn’t mention if your coffee would be filled with nitrogen or not. Curious minds...
 

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Hi CJ

I had to speak up on this one. Not criticizing you or anyone.

Tire pressure has everything to due with suspension setup. I race motorcycles and for many years raced Porsche 911s. I manage a fleet of tractor trailers and motor coaches. I spend $60k on tires. Let me tell you, getting the right tire pressure is down right a science, and suspension is only one part of the equation.

For every vehicle, the tire is integral to the suspension. It's a major component of the suspension. Some will even go so far to say the tire is the most important part of the suspension. The tire absorbs impacts, conforms to the road, provides all the traction, and on and on. The air pressure is critical to all of this, and it varies by vehicle, tire, and function.

The suspension on my race car was developed around a specific tire at 42 psi (rear tires, and everyone knows a 911 will kill you fast if you don't know how to drive it with the throttle, so air pressure is critical to handling). I run Tubliss bladders on my enduro dirt bikes so I can run 0 psi if I need more traction. The Prevost motor coaches have 105 front axle, 110 drives, 85psi on the tag axle. The 53' tri axle trailers are 125 psi. The dual axle trailers have CTIS at 110 psi.

In general, a wider tire needs more air pressure to provide a consistent contact patch. But, to your point, some tires (say a Galaxy turf tire which I use to sell) are set around 3-5 psi.

Yes, tire pressure can be adjusted for different traction as conditions dictate.

Let just all agree that tire pressures, in general, have no "absolutes". Hell, even the engineers that design tires can't agree on what the "correct" tire pressures are supposed to be. Spring rate, shock absorbers (and DON'T get me started on shocks, that's even more complicated than tire pressures), vehicle weight, suspension geometry, etc etc are all factors that directly act on the tire, thus dictate tire pressure.

Air pressure just happens to be the one thing that the common person can change. That critical air pressure will vary by tire brand, composition, size, vehicle, road surface, temps, maybe even the position of the moon. Pretty sure on the moon part.

I'll spend some time on tires when we start seeing the CTs drop. The overall efficiency of the CT will vary greatly with tires (and tire pressures).

And we haven't even touched on filling tires with nitrogen!!!

I'm out. Off to find another cup of coffee.
We aren't talking about race cars where you don't care about tread life and you will sacrifice it for grip. We are talking pickup trucks in which you can swap tires out with different brands of the same size and the pressure required doesn't change. Truck manufacturers recommend a tire pressure that is usually around the middle of your load range. So, if your truck weighs 7,000 pounds and you have a max payload of 3,000 pounds, the pressure on the door jam will be for around 8,500 pounds. But, if you want, you can get very precise on what pressure the tires should have in them.

For example, if the tires load limit is 2,800 pounds at 80 psi, and the load on the front axle is 4,200 pounds, and 5,600 pounds on the rear axle, you would want 60 psi in front and 80 psi in the rear.No change in the suspension will change the pressure you need in the tires.
 

CappyJax

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That's not the largest part of how weight of the tire will impact rolling resistance. A heavier tire takes more energy to flex; and it's unsprung weight, so it deforms itself more because its own weight is dynamic while the sprung load acts more static.

Like I said, it's complicated.

-Crissa
You are assuming that a heavier tire is stiffer than a lighter tire, and that isn't the case. They claim kevlar tires are tougher, so they may actually be stiffer.

Yes reducing unsprung weight will reduce rolling resistance, but again, it is going to be relatively insignificant.
 

Dids

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You are assuming that a heavier tire is stiffer than a lighter tire, and that isn't the case. They claim kevlar tires are tougher, so they may actually be stiffer.

Yes reducing unsprung weight will reduce rolling resistance, but again, it is going to be relatively insignificant.
According to the marketing material... up to 20% reduction. 🙂
 

Billyboy

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Wow. I'm sure all the research, calculations, and editing was significant. Well done.

When it came to battery size estimations ( @19:06 sorry on mobile no link ). I want the final estimation to be true

100 kWh for single motor
120 kWh for dual motor
200 kWh for triple motor

Then @nxt garage talks about road tire estimations. I wasn't clear why there were estimations for road tires...

Then, does this suggest replacing the theoretical Goodyear wrangler mt/r with comparable road tires would increase the range?
Yes
 

drscot

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In my case it depended completely on the local cost of gas at the time which was $2.75/gal vs the utility rate at my house which is $0.108/kWh and I assumed 100% home charging. So over the course of a year it would average up to more then $50/mo due to road trips, camping, hunting. So the 1/3 rule is probably pretty close. Given the cheapness of our local electric rates and having the 1/3 rule probably work out, I'd assume those who pay more then $0.108/kWh would end up a bit over 1/3...maybe something closer to 1/2 saving. Then again...where the electricity cost more, the gas probably does too, so it might be a wash.
[/QUOTE

Sometimes our rates are as low as 5 cents per KWh. I wonder if there is a way to determine those times and only charge preferentially? I don't drive a lot so it would be feasible if possible on a fairly automated basis.
 

fritter63

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Sometimes our rates are as low as 5 cents per KWh. I wonder if there is a way to determine those times and only charge preferentially? I don't drive a lot so it would be feasible if possible on a fairly automated basis.
Of course.... it is a setting on the charging screen when you open the charge port. Your cheap rates should be on a fixed schedule published by the utility. Our "off peak" starts at midnight, so we have have the cars set to start at that time. You can also tell it your "leave by" time, and it will figure out when to start so your car is ready by then, but I don't find that very useful.

IMG_0063.JPG
 

Greg

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Question about FSD..... will FSD have any negative effect on mileage range when engaged over a long trip?
 

Crissa

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Question about FSD..... will FSD have any negative effect on mileage range when engaged over a long trip?
Generally even cruise control is more efficient than a human driver. Autopilot and FSD would be even moreso.

They won't hypermile or anything, but computers are really good at holding a steady speed.

-Crissa
 

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