Ford Fusion Lightweight Concept

[Danoff]

Sorento: 235
Picanto: 165
CLA: 225
Roadster: 175/225 (F/R)
911 Turbo: 245/305 (F/R)
Megane: 225

Fusion: 155 (if the article above is correct)

Ok, let's take a look here.

The 911 is standout in terms of width (also has the best stopping distance by a good margin).
The Tesla was on a damp track, I say we toss it.

For braking, the front tires are really what matters, so let's list the widths that we have left

Fusion Lightweight:--155
Picanto:-------------165

CLA:--------225
Megane:----225
Sorento:----235

911 Turbo:--245

Excluding the Picanto and the standout 911, the widths are in fact similar. Let's look at weight:

Picanto:--------------2000 lbs


Fusion:---------------2700 lbs (that's a fiesta)
Megane:--------------2800 lbs

CLA:------------------3300 lbs
911 Turbo: -----------3600 lbs (0.0)
Sorento:--------------3600 lbs



The heavier cars can stop faster than the Picanto because? What do you think would happen to the stopping distance of the Megane (most comparable weight to the fusion lightweight) if you cut over 30% of the width of the tire? That's what the fusion lightweight is. Will the fusion lightweight stop in the same distance as the Picanto with narrower tires* and an extra 700 lbs? No. The megane kicks tail in the stopping distance because... lighter than the other guys AND maintains the tire width.

Ford took a bunch of weight off of the lightweight Focus, and once they did that they had the potential to make it stop like a 911**. Instead it'll stop worse than a Picanto.


* Assume the same compound
** It's possible the 911 is getting some downforce benefit, but for 60-0 I kinda doubt it's significant.

 

[niky]

I think I see where you got the number from, and you're comparing a much heavier 19" rim to a 15" rim. So in addition to the weight increase from being wider, it also has a massive weight increase for diameter.

My initial answer was going off of what I've seen over the past few years of brake testing. Wider tires simply don't make for better braking distance, not without accompanying changes in tire compound and construction.

I did read that C&D test before, but I found it while looking for another test (GRM, I believe, or Sport Compact Car) where they did brake and handling testing for different size tires. It's been so long that I can't recall if I read it online or in print.

 

[Keef]

That's not really a scientific comparison. The size of the brakes, as @Eunos_Cosmo points out, is not really that much of a factor because every car can lock up the wheels on braking. The size of the contact patch is directly related to friction so it has to be a factor.

Yea you might get some standing water benefits with a narrower tire, but I'm primarily concerned with stopping distance on dry pavement.

Like I posted earlier, there's more to it than the "size" of the contact patch. The shape of it is just as important, if not more.

Tall, skinny tires have a contact patch arranged longitudinally which is in the direction of braking and acceleration. Short, wide tires have a contact patch arranged laterally which is the direction of cornering forces.

The tires on this concept Fusion are taller and skinnier than the standard Fusion tires. While their contact patch may not be as large overall, it is oriented in a better direction for braking and acceleration. Plus, the car is quite a lot lighter which means much less friction is needed to halt the car, making the overall smaller contact patch a null point no matter which direction the forces are coming from.

EDIT: @Danoff , you cite the Porsche as having the best stopping distances by a good margin. It does. Then you say you want to look at the front tire size because it's the most important. Problem is, that's not nearly as true for the Porsche as it is for the other front-engined, front-drive cars.

The main reason Porsche cars always have stellar stopping distances if because of their fore-aft weight distribution. Whereas most front-drive cars have a weight distribution of around 60/40%, Porsches are the complete opposite. Therefore, weight during braking is already distributed 20% more evenly than front-drive cars. You'll notice that all Porsches (and many mid-engined cars as well) have oddly skinny front tires. The reason is because they can. The front tires are skinnier because they don't have to create as much friction to brake just as hard or harder than other cars as they carry much less weight under braking than other cars.

My point is that the Porsche is not a fair comparison because you're introducing at least one other factor into the equation which is a drastically different weight distribution than the other front-drive cars listed, all of which are basically the same in that measure.

Yes, I know @homeforsummer mentioned Porsche first, but he shouldn't have either. Other than that, the rest of his argument is sound.

 

[homeforsummer]

The heavier cars can stop faster than the Picanto because?

There are too many variables to say with any certainty. The Picanto is a particularly narrow car with a short wheelbase and soft suspension. It may simply be using its brakes less effectively than the other cars - or, as I pointed out, it's on eco tires (Hankook Kinergy Eco, to be specific), which aren't known for generating much grip.

Hell, that just raises another point - there's often significant difference between brands of tire, all in exactly the same size. Or tread patterns. I've almost certainly got a proper tire test somewhere in my archives, but my desk is already covered with magazines and I'm loathe to find any more...

What do you think would happen to the stopping distance of the Megane (most comparable weight to the fusion lightweight) if you cut over 30% of the width of the tire? That's what the fusion lightweight is.

I'm not sure. But if you take a Fiesta with 195-section tires (30mm less than the Megane) it stops in exactly the same time.

In fact, if you'd like another cat for your yard of pigeons, the Fiesta actually stopped from 70 mph in a shorter distance than the Megane. It's about 600 lbs lighter, for the record.

Will the fusion lightweight stop in the same distance as the Picanto with narrower tires and an extra 700 lbs? No.

Of course not, but then I'm not claiming it is. What I'm saying is that because it doesn't have that extra 700 lbs, it doesn't need the extra width. All those cars stop in the 3-second range from 60 mph, even though they're all completely different vehicles, on different brands of tire, with different suspension setups etc. The 911 is the only real anomaly and it's a few sniffs away from being a race car in terms of tire compound, suspension and the like.

Ford took a bunch of weight off of the lightweight Focus, and once they did that they had the potential to make it stop like a 911. Instead it'll stop worse than a Picanto.

Pure speculation. On 19" rims and modern tire technology it could stop as quickly as the aforementioned Fiesta.

 

[niky]

The 911 is standout in terms of width (also has the best stopping distance by a good margin).

Most 911s come on Pilot Sports. Some come on Cups. Which make for very nice braking distances, whatever width you buy them in.

And... a 911 has a rearward weight bias, which means that it can more effectively use its rear brakes to stop than almost any other car on the road.

The heavier cars can stop faster than the Picanto because?

1. The Picanto's tires suck, because they're economy tires, and don't have grippy rubber compounds.

2. The Picanto is a lightweight, front-heavy car with grabby rear brakes (non-ABS Picanto hatchbacks tend to step out very easily under braking). Too much rear brake bias and too little weight pressing the rear tires into the ground means those rear brakes spend more time up in the air and triggering the ABS and less time stopping.

The megane kicks tail in the stopping distance because... lighter than the other guys AND maintains the tire width.

The Megane has serious stopping hardware, a stiffer suspension than the Picanto, which prevents dive and allows the rear brakes to work better, and Michelin Pilot Sports... which don't come in 155mm width, sadly.

Ford took a bunch of weight off of the lightweight Focus, and once they did that they had the potential to make it stop like a 911**. Instead it'll stop worse than a Picanto.


* Assume the same compound
** It's possible the 911 is getting some downforce benefit, but for 60-0 I kinda doubt it's significant.

A Fusion will never stop as well as a 911, not without a complete redesign.

And no, we don't know if it'll stop worse than a Picanto... it'll probably stop better, considering much of the weight came off the front, making for more balanced braking... but there's really no way of telling without knowing how good or bad the actual tires are in real world use.

 

[Danoff]

Of course not, but then I'm not claiming it is. What I'm saying is that because it doesn't have that extra 700 lbs, it doesn't need the extra width.

...over the picanto, it does have an extra 700 lbs, but less width than the picanto.

 

[Danoff]

Most 911s come on Pilot Sports.

God I love my Pilot Super Sports.

Some come on Cups. Which make for very nice braking distances, whatever width you buy them in.

It's a fair point. I got caught up in using @homeforsummer's data against him.

And... a 911 has a rearward weight bias, which means that it can more effectively use its rear brakes to stop than almost any other car on the road.

It was hyperbole on my part. You have to read that line with some tongue in cheek. I suppose I should have tagged it to come across better.

1. The Picanto's tires suck, because they're economy tires, and don't have grippy rubber compounds.

Ok, but what are we expecting ford to put on their high mpg super efficient green car?

The Megane has serious stopping hardware, a stiffer suspension than the Picanto, which prevents dive and allows the rear brakes to work better, and Michelin Pilot Sports... which don't come in 155mm width, sadly.

Totally fair point and it pretty much tosses all of @homeforsummer's data out the window.

And no, we don't know if it'll stop worse than a Picanto... it'll probably stop better, considering much of the weight came off the front, making for more balanced braking... but there's really no way of telling without knowing how good or bad the actual tires are in real world use.

No way, 700 lbs, thinner tires, same compound, it'll stop slower.

 

[niky]

Depends. I'm betting it'll stop better because, for one, it's got more rear weight, it has a more sophisticated ABS system and likely stronger stoppers with more intelligent electronic brake distribution software, and then there's the pressure on the contact patch, which will be better on the Fusion, because of the extra weight versus the Picanto.

It's a fair bet it won't stop as well as the standard Fusion, but then, again, it's a toss-up as to whether that'll be due to the tire size or the tire compound. More likely the latter.

 

[Keef]

The heavier cars can stop faster than the Picanto because?

Because it has 14 inch wheels. Despite the wider tires, the Picanto still has a smaller contact patch than the Fusion concept. That's okay because the car is lighter, except that the shape of the contact patch is not very well oriented in the direction of braking forces. These two factors, the small diameter and poor shape of the contact patch, allow the tire to succumb to locking up much easier because of increased braking torque and less grip in that direction, respectively. The ABS kicks in easier, increasing stopping distance. Boom.

What do you think would happen to the stopping distance of the Megane (most comparable weight to the fusion lightweight) if you cut over 30% of the width of the tire?

Stopping distance would increase.

That's what the fusion lightweight is.

It's NOT, as I've explained three times now. The Fusion lightweight doesn't simply have skinnier tires. It has skinnier, TALLER tires. While the contact patch is smaller overall, it's actually longer longitudinally and combined with the lighter weight this maintains braking performance.

Will the fusion lightweight stop in the same distance as the Picanto with narrower tires* and an extra 700 lbs? No.

Probably better actually because it's considerably taller tires won't fall victim to the Picanto's problems I mentioned above.

The megane kicks tail in the stopping distance because... lighter than the other guys AND maintains the tire width.

The Megane also has 18 inch wheels. They're about the same size tires as a normal Fusion. So it brakes better than a normal Fusion with the same size tires because it's lighter.

** It's possible the 911 is getting some downforce benefit, but for 60-0 I kinda doubt it's significant.

[/quote]
As an aside, Porsche 911s are actually rather lifty. They're shaped just like a wing, pointy rear end and all. That's why they've historically had big giant spoilers and wings hanging off the rear, to counteract the rather strong lift created by their shape.

 

[homeforsummer]

Totally fair point and it pretty much tosses all of @homeforsummer's data out the window.

Not really. I mentioned several variables myself in the post you partially quoted. I mentioned that the Megane was one of the best hot hatchbacks of its era, that the Picanto was a budget city car (with budget city car suspension), and that the Porsche is virtually a race car. Nothing in the post you quoted of niky's actually disagreed with anything I said, in fact.

You've not so much let yourself got caught up in using my data against me, as let yourself get caught up in using your own assumptions (not backed by any data) cloud your objectivity.

Anyway, feel free to believe what you like - myself, niky and Keef have all explained why what you're saying isn't correct but you're apparently more bothered about defending your opinions than you are about learning something.

 

[Danoff]

Because it has 14 inch wheels. Despite the wider tires, the Picanto still has a smaller contact patch than the Fusion concept. That's okay because the car is lighter, except that the shape of the contact patch is not very well oriented in the direction of braking forces. These two factors, the small diameter and poor shape of the contact patch, allow the tire to succumb to locking up much easier because of increased braking torque and less grip in that direction, respectively.

I'm counting one factor there.

It's NOT, as I've explained three times now. The Fusion lightweight doesn't simply have skinnier tires. It has skinnier, TALLER tires. While the contact patch is smaller overall, it's actually longer longitudinally and combined with the lighter weight this maintains braking performance.

Yea I saw your posts, but you're making some assumptions that I don't like and then it doesn't jive well with my understanding of physics. First, you assume the the contact patch is longer because of the increased diameter. Maybe it is, maybe it isn't. That would depend on the stiffness of the sidewalls and tire pressure I would imagine. For the same tire pressure and sidewall stiffness you're probably right. But not by a lot. You say the lightweight fusion has a larger contact patch than the Picanto, but I don't know how you can know that.

The other thing is that what matters is the surface area of rubber in contact with the road, not the orientation. Maybe there is some sort of car dynamics that I'm not familiar with here because my background is in physics rather than cars, but I don't see how the orientation of the contact patch matters for total frictional force generated. I have a feeling I'm going to learn something here, so feel free to post an article explaining the effect you're talking about.

Not really. I mentioned several variables myself in the post you partially quoted. I mentioned that the Megane was one of the best hot hatchbacks of its era, that the Picanto was a budget city car, and that the Porsche is virtually a race car. Nothing in the post you quoted of niky's actually disagreed with anything I said, in fact.

No, I did that in the post that quoted you, rather than @niky.

You've not so much let yourself got caught up in using my data against me, as let yourself get caught up in using your own assumptions (not backed by any data) cloud your objectivity.

Interesting that you would say that given that your data, at best, supported me.

Anyway, feel free to believe what you like - myself, niky and Keef have all explained why what you're saying isn't correct but you're apparently more bothered about defending your opinions than you are about learning something.

I keep seeing attempts that confuse other issues, I haven't seen anything explaining why what I'm saying isn't correct.

 

[niky]

In terms of absolute grip, granted, the total surface should be the only thing that matters, but the orientation of the patch has an effect on how the tire responds to either lateral or longitudinal forces. A longer patch gives more tractive grip and more braking grip. Again, this is why drag radials are tall... and why the manufacturers picked a very tall 19" wheel size for these tires... also the tall size minimizes the flexing where the round tire has to lie flat against the ground... minimizing heat build up in the tire carcass and minimizing rolling resistance further.

Patch shape also matters because patch size doesn't always change in a purely linear fashion under different loads and tire pressures.

Again, it's entirely possible braking will be negatively affected. But again, if it is, it will be because of what kind of tires are on there rather than what width.

 

[Danoff]

In terms of absolute grip, granted, the total surface should be the only thing that matters, but the orientation of the patch has an effect on how the tire responds to either lateral or longitudinal forces. A longer patch gives more tractive grip and more braking grip.

Don't follow. Friction force is what you want, that's determined by surface area.

Again, this is why drag radials are tall... and why the manufacturers picked a very tall 19" wheel size for these tires...

Tall tires would be good for reduced rolling resistance while attempting to maximize the contact patch. I get that. That doesn't explain why the orientation of the contact patch matters for braking.

also the tall size minimizes the flexing where the round tire has to lie flat against the ground... minimizing heat build up in the tire carcass and minimizing rolling resistance further.

Not 100% sure I followed, but this seems to be what I said above.

Patch shape also matters because patch size doesn't always change in a purely linear fashion under different loads and tire pressures.

That's not an argument about the contact patch shape as much as it is about the tire dimensions. The goal is still to put as much surface area on the ground as possible. Still this is an argument that suggests that your patch might grow faster under braking with a taller thinner tire than with a shorter wider tire. But we know for certain that the shorter wider tire starts out with a larger contact patch, so it doesn't have to grow as fast under braking to maintain an advantage.

Again, it's entirely possible braking will be negatively affected. But again, if it is, it will be because of what kind of tires are on there rather than what width.

You cannot sit there and tell me that width (contact patch size) has no effect on braking. Stop talking about the compounds and focus on the geometry. The contact patch is reduced by a massive percentage (and as a result, frictional force is also reduced by a massive percentage, albeit potentially a nonlinear correlation). Some of the patch size is bought back by increasing the diameter, but there's no way it's close. You can't tell me that dropping the tire contact patch is going to have no effect on braking - the contact patch is what determines your braking force!

 

[niky]

But we know for certain that the shorter wider tire starts out with a larger contact patch, so it doesn't have to grow as fast under braking to maintain an advantage.

Ideally, the contact patch should be the same size for both tires, given the same weight of car and the same tire pressure. In the real world, yes, adding width or height will still make the patch bigger even with the same pressure and weight.

Here is the problem... you're making the assumption that the width of the shorter tire has more effect than the height of the narrower one. Without firsthand data, none of us know which has the greater effect. Also, the effect of width on patch size is not a strictly linear thing... there are limits to how much the patch grows with extra width, and differing tire constructions and shapes (square shoulder versus round... flatness of the tread area and stiffness of the carcass... tread design) will have a profound effect on that.

Some of the early Ecopia tall and narrow concepts I've seen have even done away with most of the tread grooves down the center. Like motorcycle tires, the concept is narrow enough not to need as much void area for water drainage as wide car tires. Which grants it even more contact patch.

 

[Danoff]

Ideally, the contact patch should be the same size for both tires, given the same weight of car and the same tire pressure. In the real world, yes, adding width or height will still make the patch bigger even with the same pressure and weight.

Why would the "ideal" world result in the same contact patch for the one tall skinny tire and one shorter fat tire given the same weight and tire pressure? Extra width goes 100% to the contact patch. Extra height results in a fractional increase in contact patch.

Here is the problem... you're making the assumption that the width of the shorter tire has more effect than the height of the narrower one. Without firsthand data, none of us know which has the greater effect. Also, the effect of width on patch size is not a strictly linear thing... there are limits to how much the patch grows with extra width, and differing tire constructions and shapes (square shoulder versus round... flatness of the tread area and stiffness of the carcass... tread design) will have a profound effect on that.

Some of the early Ecopia tall and narrow concepts I've seen have even done away with most of the tread grooves down the center. Like motorcycle tires, the concept is narrow enough not to need as much void area for water drainage as wide car tires. Which grants it even more contact patch.

Ok that's fine. If that's the answer then I can accept that. If the narrower tires on the focus lightweight allow for the same contact patch because of the tread design that's a legitimate answer. I seriously doubt that you can design significantly different tread patterns when going from something like 255mm to 155mm in width, but if that's the answer, and the contact patch is similar in surface area, I'll accept that I'm wrong.

 

[niky]

Why would the "ideal" world result in the same contact patch for the one tall skinny tire and one shorter fat tire given the same weight and tire pressure? Extra width goes 100% to the contact patch. Extra height results in a fractional increase in contact patch.

Given the same load and tire pressure, the contact patch should remain the same in terms of area, no matter what the shape of the tire is. No matter how wide or tall the tire, the contact patch area should remain the same, with only the shape of the patch changing.

This is ideally. But since tires aren't ideal ballons, that doesn't happen. You can make wider tires that have bigger contact patches than ideal laws dictate. You can also make taller ones that do the same, too.

 

[Danoff]

Given the same load and tire pressure, the contact patch should remain the same in terms of area, no matter what the shape of the tire is. No matter how wide or tall the tire, the contact patch area should remain the same, with only the shape of the patch changing.

This is ideally. But since tires aren't ideal ballons, that doesn't happen. You can make wider tires that have bigger contact patches than ideal laws dictate. You can also make taller ones that do the same, too.

Well, ok, if you ignore the geometrical constraints of the shape of the tire then sure, they should all have the same contact patch because we can assume that they are all balloons. I didn't realize you mean that ideally the contact patch was not constrained by the geometry of the tire.

 

[Danoff]

Ok that's fine. If that's the answer then I can accept that. If the narrower tires on the focus lightweight allow for the same contact patch because of the tread design that's a legitimate answer. I seriously doubt that you can design significantly different tread patterns when going from something like 255mm to 155mm in width, but if that's the answer, and the contact patch is similar in surface area, I'll accept that I'm wrong.

Here's how I know that you can't maintain the frictional force when going from 255mm to 155mm... people still sell wider tires. The more the frictional force matters (Porsche), the wider (not taller) the tires. If you could redesign thin tires to maintain the same braking distance but increase fuel economy - everyone would do it and it would be on race cars.

 

[Keef]

Here's how I know that you can't maintain the frictional force when going from 255mm to 155mm... people still sell wider tires. The more the frictional force matters (Porsche), the wider (not taller) the tires. If you could redesign thin tires to maintain the same braking distance but increase fuel economy - everyone would do it and it would be on race cars.

Race cars don't just brake. They turn. They need lateral grip. When a car brakes the weight pushes down on the tire, expanding the footprint in all directions, mostly longitudinally. But when a car turns it doesn't necessarily do that, partly because there's not as much weight pushing it down compared to braking hard, suspension geometry, and tire sidewall roll, which means the tire won't meet the ground at a right angle. While turning a tire's footprint can actually get smaller unless the alignment is adjusted for this eventuality. Braking doesn't pose the same problem because anti-dive geometry pits the two front suspensions against each other, reducing funny geometry, and the sidewalls don't roll but squish down instead.

Therefore, cars that don't demand high cornering forces but do need emergency stopping ability can get away with skinny tires whereas race cars that focus on cornering grip can't.

I'm working on finding some sort of article to explain the shape vs. size thing.

 

[Danoff]

Race cars don't just brake. They turn. They need lateral grip. When a car brakes the weight pushes down on the tire, expanding the footprint in all directions, mostly longitudinally. But when a car turns it doesn't necessarily do that, partly because there's not as much weight pushing it down compared to braking hard, suspension geometry, and tire sidewall roll, which means the tire won't meet the ground at a right angle. While turning a tire's footprint can actually get smaller unless the alignment is adjusted for this eventuality. Braking doesn't pose the same problem because anti-dive geometry pits the two front suspensions against each other, reducing funny geometry, and the sidewalls don't roll but squish down instead.

Therefore, cars that don't demand high cornering forces but do need emergency stopping ability can get away with skinny tires whereas race cars that focus on cornering grip can't.

The loaded tires still squash. Cars don't get much out of the rear when it comes to braking, and you won't get much out of some tires when cornering, but the weight gets distributed and the footprint increases and the loaded tire squashes.

Braking and turning generally give you a similar total contact patch (though not if you're doing them simultaneously). As a result, you can generally pull about 1g braking or turning. I maintain that the orientation of the patch doesn't matter as the force is calculated based on the surface area of the patch (surface area of all patches combined really).

 

[niky]

Ideally, the shape doesn't matter in terms of the total friction generated, but it still affects the stability of the contact patch. If the contact patch is aligned with its wider dimension along the line in which you are trying to push the tire, it helps keep the patch more stable... but tread blocks also matter here... not just in terms of void area but orientation and stiffness.

-

But this all strikes me as so much ado over so little. What really matters is how well these 155mm wide tires stop in the real world. And here's some actual data:
http://www.autoexpress.co.uk/bmw/i3/85322/bmw-i3-vs-rivals-electric-car-triple-test

To note... WhatCar says that the i3 they tested braked in much less distance than the Ampera they tested... http://www.whatcar.com/car-news/bmw/i3/bmw-i3-vs-vauxhall-ampera/1292236

...but they don't publish numbers online... so this is all I can find.

The i3 is heavier than the Fusion concept, and actually comes on the same size tall and narrow tires, and while the braking distance isn't great, it's within the same range as most non-performance cars out there of the same weight. (Here's a sample: http://www.autoexpress.co.uk/honda/civic/40864/honda-civic-vs-focus-and-golf-specifications ...the Golf TDi actually brakes worse...)

So, again, I doubt the braking will be completely rubbish. And if it is, it won't be simply because the tires are narrow.

 

[Tornado]

So, wait. If narrowing down the tires of a car since a wider contact patch is theoretically no longer needed to give comparable performance to competitors is a "compromise in safety", doesn't that carry the further implication that any car which doesn't stop as well as a Porsche 911 or an extremely hot hatch is similarly "compromised in safety"?

Because unless that is being argued as well, I certainly don't see what the point is of a page and a half of "Prove my unbacked assertion wrong with numbers" "Okay, here's some numbers from multiple tests as well as some direct anecdotes" "No, that isn't good enough" ad nauseum.

 

[Eunos_Cosmo]

I think the gist is that it is not as safe as it could be.

 

[Tornado]

No car is as safe as it could be, and it doesn't take something like your Cobalt shutting off on you at 75 on the thruway to know that there were compromises made in its development; so what is the baseline for what constitutes "not safe enough" if "has performance theoretically as good as its contemporaries" does not?






Why does the BreezeFrees come with 215/45WR17 wheels with Michelin Primacy tires literally straight off a Prius all around? Did you know that in certain cases, those poor tires can cause the car to have oversteer? No no. That simply won't do. It would be much safer if it came with something like the 275/35 ZR18, 335/30ZR18 and Michelin Pilot Sports that the original Dodge Viper had. Then the car would certainly stop a lot quicker than 172 feet from 70 MPH.


Well, probably.

 

[Beeblebrox237]

Guys, the width of a tyre makes virtually no difference in the size of the contact patch. Skinny tyres are just as safe as fat ones, but it all depends on how the tyres are designed, the weight of the car, and the tyre pressure.