Comparing new Roadster exterior dimensions to original Roadster

[ggnykk]

5th data set:
Using 1500 pixel wide image from The new Tesla Roadster is the halo car for the entire EV industry (+360 Test drive)
I get (edge of rubber to edge of rubber)
Front wheel: 209 pixels / 28.3" real 28.24 calculated from ideal rear wheel
Rear wheel: 222 pixels /30 " real/ 30.06" calculated from ideal front wheel.
Wheelbase: 877 pixels/ 118.75 based on front wheel, 119.86 based on rear wheel
Wheel well to wheel well: 645 pixels/ 87" based on front wheel

Michelin official specs say rear tire overall diameter is only 28.7 inch, how you get 30 inch? Remember 28.7 inch not only include the visible tire side wall, but also include the tire tread that sticks out from the tire (which you can't see or measure clearly in the picture).

Your math is clearly wrong coz 118.75 inch is clearly outside of the range from 105.7 inch up to 114.9 inch that I defined earlier using wheel rim calculation. 118.75 inch is also 2 inch LONGER than Model S and X, which is impossible.

That's why I use the rear wheel well as the most accurate way to doing the math here, like what I have laid out previously. I really think the wheel base fall anywhere between 110 inch to 114 inch for the new roadster. It is possible that Tesla just use the same wheelbase as Model 3 for the new roadster in length, and only make it wider in width.

 

[mongo]

Michelin official specs say rear tire overall diameter is only 28.7 inch, how you get 30 inch? Remember 28.7 inch not only include the visible tire side wall, but also include the tire tread that sticks out from the tire (which you can't see or measure clearly in the picture).

I got that from what a 325/35-R21 tire is supposed to be (325*.35/25.4)*2+21. I searched web for Michelin reference, but did not see one. Would be happy to correct with a reference (sure you are not thinking of 325/35 R20).
Do you have a front diameter? In my measurement they both matched the expected.

Your math is clearly wrong coz 118.75 inch is clearly outside of the range from 105.7 inch up to 114.9 inch that I defined earlier using wheel rim calculation. 118.75 inch is also 2 inch LONGER than Model S and X, which is impossible.

How is my estimating the edge of rubber on a larger measurement any worse that your guessing the tire bead seating surface on a smaller measurement?

Why does my number not matching your number make my number wrong?

Why is it impossible to have a longer wheelbase?

That's why I use the rear wheel well as the most accurate way to doing the math here, like what I have laid out previously. I really think the wheel base fall anywhere between 110 inch to 114 inch for the new roadster. It is possible that Tesla just use the same wheelbase as Model 3 for the new roadster in length, and only make it wider in width.

How can you call that accurate when you are guessing what the gap is?

So you can add one inch on the left and one inch on the right for clearance.

I realize I may be slightly off in capturing the tread edge. However, the margin of error is <=5 pixels out of 200+ so 2.5% max. 97.5%*118.5=115.5.

 

[mongo]

You are correct that it is hard to know exactly how to count the rear wheel 21 inch rim. I did thought about that when i did the pixel count, and had a range of estimates. The "21 inch rim" could range from 160 pixels up to 174 pixels, depend on exactly where you count the "rim". So that means the 876 pixels wheel base could range from 105.7 inch up to 114.9 inch. (that is the min and max range)

I get 156 pixels for the bead seat, which comes out to 21.08 - 21.12 based on my previously measured tire sizes.

 

[shokunin]

To me, the front tire looks to be 265/35/20 and not 295/35/20 as some have reported, not sure if that affects your calcs. I don't think Michelin even makes a 295/35/20 Michelin Pilot Sport Cup 2.

A 265 should have a diameter of 27.3" and the 325 a diameter of 28.7".

 

[mongo]

To me, the front tire looks to be 265/35/20 and not 295/35/20 as some have reported, not sure if that affects your calcs. I don't think Michelin even makes a 295/35/20 Michelin Pilot Sport Cup 2.

A 265 should have a diameter of 27.3" and the 325 a diameter of 28.7".

I'm using 265/35/20 in front 325/35/21 in rear. But my use of tire calculators says there are 28.3 and 30 inch respectively. I haven't found manufacturer data on the rears. Where did you get those diameters from?

 

[shokunin]

I'm using 265/35/20 in front 325/35/21 in rear. But my use of tire calculators says there are 28.3 and 30 inch respectively. I haven't found manufacturer data on the rears. Where did you get those diameters from?

I've attached the spec sheet from Michelin.

 

[mongo]

I've attached the spec sheet from Michelin.

Thanks. I found the problem. The post I pulled tire data from had a typo it said they were 325/35/21 but the picture shows they were really 325/30/21 which fits the data sheet at 28.7".

@ggnykk My measurements may be off by ~4.5%. Which puts the wheelbase at around 113 and lines up with your results. Which is weird since the front and rear were in the right ratio. The render may not have the same tires? While redoing measurement in Solidworks, I noticed that the render has perspective which may be skewing things too.


Still looks like barely enough area for 200kWh.

 

[shokunin]

What do you guys think of RegoApps size comparison:

Tesla Roadster vs Model S size comparison • r/teslamotors

 

[Brando]

How can 200kwh worth of batteries fit in this car? It seems like there's not enough room to fit two stacks of 100kwh packs under there without the car being wider and longer or at least taller. ...

I'm blown away by all the specs on this car, but 10,000NM of torque? That's over 7000 lbft, so something like 28 times my roadster? Really? Sounds like a typo! Perhaps in order to exceed 250mph while also breaking 2 seconds in the 0-60, extreme torque was necessary to overcome the very tall gearing? I think it's got to be that while this much torque is technically achievable by the motors, it's not possible to apply this much torque without wheel spin.

computer controlled, traction control = little, if any, wheel spin [right?]

 

[Colasec]

Thanks, mongo@ and friends. Can you take a shot at the height as well, please? And maybe distance from the ground to the floor pan?

 

[mongo]

Thanks, mongo@ and friends. Can you take a shot at the height as well, please? And maybe distance from the ground to the floor pan?

I'm wary to do that because the artificial perspective may give false numbers, but if I can figure out what the scale should be, I'll try.

 

[gregd]

I'm wary to do that because the artificial perspective may give false numbers, but if I can figure out what the scale should be, I'll try.

Ground clearance is probably the next most important dimension to figure out. At first glance, the new car may have the same problem with curbs, driveways, speed bumps, etc. that make driving the current car a bit too, um, "tactile". No word if the car will have SAS or not, but I'm guessing not (for weight).

I have a 1x6" piece of wood at the base of our downward-sloping driveway that I drive over in order to not bury the nose of the car in the garage floor as I enter...

 

[Carl W]

Ground clearance is probably the next most important dimension to figure out. At first glance, the new car may have the same problem with curbs, driveways, speed bumps, etc. that make driving the current car a bit too, um, "tactile". No word if the car will have SAS or not, but I'm guessing not (for weight).

I have a 1x6" piece of wood at the base of our downward-sloping driveway that I drive over in order to not bury the nose of the car in the garage floor as I enter...

I have a convoluted downhill driveway that requires me to alway enter my driveway from one direction in order to not scrape. So when I come from the other direction, I have to U-turn. I think my neighbors wonder about my sanity "did he miss his house again???"

 

[Carl W]

computer controlled, traction control = little, if any, wheel spin [right?]

I agree that traction control will prevent wheel spin (though in the videos, sounds like the wheels chirp!). By the numbers, though, I'd think that there's 10 times more torque available than will ever be allowed to drive the car. I pity the person than turns off their traction control.

 

[Carl W]

That is the subject of much speculation. Are there 2 P100DL packs under the seats? Test riders reported that it felt like they were sitting "high" in the car. They may also be banking on battery advancements in the new few years.

Yes, that is the current assumption.


That is wheel torque, not motor torque. Turns out it's only about 10% more than the SP100DL.


There are some thoughts in this thread:
Holding on to your Roadster. . .

Thanks and I wonder if your answer "yes, that is the current assumption" should have been "yes, that is the current assumption"

 

[Carl W]

I agree that traction control will prevent wheel spin (though in the videos, sounds like the wheels chirp!). By the numbers, though, I'd think that there's 10 times more torque available than will ever be allowed to drive the car. I pity the person than turns off their traction control.

nevermind. 10000NM is the wheel torque not motor.

 

[mongo]

I have a convoluted downhill driveway that requires me to alway enter my driveway from one direction in order to not scrape. So when I come from the other direction, I have to U-turn. I think my neighbors wonder about my sanity "did he miss his house again???"

The overhangs on the front and rear look fairly small, may help with approach and departure angle ( just don't go over speed bumps)

 

[Carl W]

The overhangs on the front and rear look fairly small, may help with approach and departure angle ( just don't go over speed bumps)

My problem is scraping in the middle of the bottom of the car because my driveway abruptly goes downhill from the street. However, I've got my method that works, so no worries!

 

[CarlK]

Are we sure the dual motors are in the rear? I’m expecting innlarge motor in the rear and separate motors in the front wheels.

No, because physics. The center of gravity of the car is above the axles, so at high acceleration the weight transfers to the rear axles. That means the rear wheels have a LOT more grip than the front wheels, so that's where you put the power delivery.

There's a reason most race cars are RWD! (Rally and ice racing cars are typically AWD for obvious reasons.)

Another reason would be two separate motors are needed to conduct torque vectoring on rear wheels. Steering system took care of front wheels there is little need to add torque vectoring there. May not even be desirable to do that.

 

[goldface]

Hi,
Are there any news about the official car measurements?