lightweight wheels model 3 performance 0-60 testing

[Knightshade]

Simply not true, your poor overgeneralization doesn't equate to real-world applications.

If what you said was true, I could slap 4 DOT drag radials on a car and get a ridiculous braking performance increase simply because they're more sticky and help with a launch. When in fact, that would not even be remotely the case and you would have better braking with street tires that are astronomically worse during a launch of the car.

Here's an engineering explained video that might help you out here:

He has a whole discussion about using braking distances to determine max possible acceleration times on the same street legal tires.

He even shows the math of how braking distance (since that's at max grip by virtue of ABS) tells you the grip limit of the tires for acceleration as well.

Switching from MXM4s to PS4s tires significantly improves braking distance on the P3D- suggesting the brakes were traction (grip) limited.
The same swap does NOT improve acceleration. At all. Suggesting the acceleration was NOT traction (grip) limited.

If you disagree with his math please be sure to post what equations YOU think apply to braking grip but NOT acceleration grip somehow.

(he does get into weight transfer of braking vs acceleration BTW if that's where you planned to go- but also shows that's at best a couple hundredth of a second difference either way)

Amusingly- the real reason for his video is addressing the question of if weight reduction makes a car which is otherwise grip limited faster (spoiler- it does)

 

[Sam1]

I gotta stop clicking on that 'show ignored content' button.

 

[mpgxsvcd]

I gotta stop clicking on that 'show ignored content' button.

Define “street tires”.

 

[Knightshade]

I gotta stop clicking on that 'show ignored content' button.

Yeah, sucks when it shows you physics and math proving you wrong every time I guess- much better to ignore it than try to understand it right?

 

[Sam1]

Yeah, sucks when it shows you physics and math proving you wrong every time I guess- much better to ignore it than try to understand it right?

No, because the video you posted discusses the theoretical implications of two completely different cars having the same power train with different size tires, weight variations and both sets of tires having the same exact grip amount. The video doesn't support your assertion in the slightest, and I'm guessing that you didn't actually watch the video.

Hope you have a great day, gotta pop you back in the ignore box!

 

[Sam1]

Define “street tires”.

It's the same definition that everyone in the automotive industry uses. DOT approved. Is there any other definition?

 

[gearchruncher]

 

[bedoig]

I liked the last line "I don't know why it brings me joy to make an entire video feel pointless right at the end..."

Kinda feels like this thread, lol. Ok, maybe it's most threads on TMC mostly arguing semantics

 

[Gauss Guzzler]

Tires providing better braking does not equate to better acceleration. Two completely different situations

I'm genuinely curious. Are you referring to the car's weight distribution? Or a difference in the way the ABS pump manages traction control vs anti-lock? Either way, I don't see how the tire would play any significant role in the discrepancy.

 

[Sam1]

I'm genuinely curious. Are you referring to the car's weight distribution? Or a difference in the way the ABS pump manages traction control vs anti-lock? Either way, I don't see how the tire would play any significant role in the discrepancy.

Composition of the tire itself. Tread stickiness isn't the singular factor at play. Then you get into the issue of what design works better for what surface.

 

[Gauss Guzzler]

OK, sure, directional tires could make a difference, and many drag radials are directional. But for common street/track tires I always thought the directionality was mostly about deep water shedding. Are there any with published *dry* traction differences?

 

[Sam1]

OK, sure, directional tires could make a difference, and many drag radials are directional. But for common street/track tires I always thought the directionality was mostly about deep water shedding. Are there any with published *dry* traction differences?

The tires are all built differently, even if they have the same belt count, the windings can be laid out in a different design. One may have stiffer sidewalls, one will have less stiff sidewalls, one may have a continuous compound across the entire tread block, one may change 5 compounds across the tire. A surface may like having more sipes for bite, another surface may like having larger blocks with less sipes etc.

A good example of this was the 595rs-rr tires I ran at the track on one of my old M3P's. Those things were amazing for both cornering and braking, but the PS4S of the same size was better for launches (even though the PS4S was 300tw compared to 200tw, and had less tread across the tire on the ground).

The point of the issue is that a tire's braking performance does not directly correlate with acceleration performance. I think he believed that video using a theoretical example for ease of calculation equated to fact.

 

[dfwatt]

Here's an engineering explained video that might help you out here:

He has a whole discussion about using braking distances to determine max possible acceleration times on the same street legal tires.

He even shows the math of how braking distance (since that's at max grip by virtue of ABS) tells you the grip limit of the tires for acceleration as well.

Switching from MXM4s to PS4s tires significantly improves braking distance on the P3D- suggesting the brakes were traction (grip) limited.
The same swap does NOT improve acceleration. At all. Suggesting the acceleration was NOT traction (grip) limited.

If you disagree with his math please be sure to post what equations YOU think apply to braking grip but NOT acceleration grip somehow.

(he does get into weight transfer of braking vs acceleration BTW if that's where you planned to go- but also shows that's at best a couple hundredth of a second difference either way)

Amusingly- the real reason for his video is addressing the question of if weight reduction makes a car which is otherwise grip limited faster (spoiler- it does)

I think basic Newtonian mechanics escapes a subset of our fourm members. Hard to believe that braking and acceleration both of course linear acceleration could be seen as significantly unbundled, or even worse, mechanistically unrelated. More evidence that a little knowledge is a dangerous thing

 

[gearchruncher]

Hard to believe that braking and acceleration both of course linear acceleration could be seen as significantly unbundled,

A top fuel dragster is awful at braking.
A C7 corvette with more horsepower is worse at 0-60 but better at 60-0 than the C8 corvette.
The Plaid can accelerate faster than it can brake.
Cars and tires are very non-linear systems, not simple Newtonian physics you learned in high school.

More evidence that a little knowledge is a dangerous thing

The irony is most people that love to call out the dunning-kruger effect are solidly in the non-expert phase, because actual experts are aware of how complex a topic is. When someone is on the ignorant phase of D-K, experts look like idiots because they seem to be ignoring the very simple answer and want to talk about complexity that the ignorant person doesn't even have a sense exists.

 

[Gauss Guzzler]

Well the topic was "tires", not weight distribution or electronic traction control systems. I think we all understand how those can be asymmetric.

And no evidence (or theory) has been presented to suggest that any available tires have directional traction in dry conditions other than the extreme example of drag radials which deform dramatically at very low speeds.

 

[Sam1]

And no evidence (or theory) has been presented to suggest that any available tires have directional traction in dry conditions other than the extreme example of drag radials which deform dramatically at very low speeds.

The drag radials was used because it is a simple obtuse presentation, and those are not limited to variations at low speeds. Pop a set on there and go try to cut up a canyon or road course and see how terrible your times are reduced when compared to a set of average normal street tires.

If you need a more specific, non-DR related comparison, look at the multiple pound weight differences in between the same line and brand of tire, that exist between an OEM spec tire and an open market tire. That weight isn't because they use 2 or 3 pounds less rubber, it's because (a lot of times) they will use different belt stranding and manufacturing approaches. Maybe larger winds, larger cables or thinner and tighter winds etc) because they need the tire to perform differently than the other.

One measurement of a performance metric with a tire does not by default, translate to other performance metrics.

 

[Sendit1]

A top fuel dragster is awful at braking.
A C7 corvette with more horsepower is worse at 0-60 but better at 60-0 than the C8 corvette.
The Plaid can accelerate faster than it can brake.
Cars and tires are very non-linear systems, not simple Newtonian physics you learned in high school.

The irony is most people that love to call out the dunning-kruger effect are solidly in the non-expert phase, because actual experts are aware of how complex a topic is. When someone is on the ignorant phase of D-K, experts look like idiots because they seem to be ignoring the very simple answer and want to talk about complexity that the ignorant person doesn't even have a sense exists.

This. Yes. Been there, done that, got schooled. Learned a little. Now I'm a tiny bit smarter / or a tiny bit less dumb...

 

[Knightshade]

Cars and tires are very non-linear systems, not simple Newtonian physics you learned in high school.

The irony is most people that love to call out the dunning-kruger effect are solidly in the non-expert phase, because actual experts are aware of how complex a topic is. When someone is on the ignorant phase of D-K, experts look like idiots because they seem to be ignoring the very simple answer and want to talk about complexity that the ignorant person doesn't even have a sense exists.

Hilariously the video you posted (which is another excellent one from EE, same source as I posted) at about 7 minutes in specifically says he doesn't buy the "tire tread pattern matters" for this stuff theory a certain someone keeps bringing up

Instead he points out that usually cars are power limited when accelerating, but traction limited when braking.

Which is exactly why stickier tires on the Performance 3 don't make it any faster- it doesn't NEED more traction, it can't use it- it's power limited from going quicker, not traction limited.

But better tires DO make it stop shorter- because it IS traction limited there.

The Plaid is the one production car, ever, he's aware of that accelerates faster than it brakes (though it's reasonably close) because it is traction limited on BOTH ends. It has plenty of power.

And he explains the main reason for the difference is EV launch control is a slightly quicker system than ABS at figuring out available traction. Thus when the plaid accelerates, it finds the optimal curve of doing so a little sooner than the ABS system finds the optimal curve for deceleration, thus your braking time/distance is slightly longer.

Not so in other cars, including the one we're actually discussing here where braking remains "faster" than acceleration because traction isn't the limit on acceleration... and where factually observed date show no benefit to more traction for acceleration-- which it WOULD if the car was TRACTION limited. It's not.

 

[Kvitravn]

The difference in EV launch i one thing - the torque management of a Tesla through a wet roundabout is good in isolation and a revelation compared to more traditional systems like on the BMW i4M50.

Model 3 will give that little twitch that tells you the outer rear broke traction, and then immediately revert to smooth punchy acceleration. The BMW spins up the inner front wheel, then loses a lot of power, then comes back and spins the same tire again. This then upsets the balance of the whole car so that a playful blast out of the roundabout suddenly feels like loss of control.

I gapped a collegue in his i4M50 so massively in the wet he's probably never want to play with me ever again

 

[Sam1]

The difference in EV launch i one thing - the torque management of a Tesla through a wet roundabout is good in isolation and a revelation compared to more traditional systems like on the BMW i4M50.

Model 3 will give that little twitch that tells you the outer rear broke traction, and then immediately revert to smooth punchy acceleration. The BMW spins up the inner front wheel, then loses a lot of power, then comes back and spins the same tire again. This then upsets the balance of the whole car so that a playful blast out of the roundabout suddenly feels like loss of control.

I gapped a collegue in his i4M50 so massively in the wet he's probably never want to play with me ever again

Yeah, there's some kind of misunderstanding with Tesla's system that the light has to be on for traction control to be working. It does not. The TC on a Tesla is the best of any system I've ever seen.

Making an assumption here, but I believe that when the light is on, that means it's slipped enough to the point where the brakes are in use. Before the light, it's just the computer pulling power.