[Slickshift99]

It’s been a tradition with super-cars to have wider and slightly larger wheels at the rear than compared to the front, to aid the RWD setup for greater performance and safety. Going after the various benefits such system has to offer, many luxury RWD sedans adopted this norm too, say the 530D.

Here my notion is, will the vice versa benefit as good on Fwd cars?
i.e. upsizing the front wheels by an inch or two, increasing width say from 165 to 185 while letting the stock wheels be on the rear for comfort point of view. Thus offering greater performance and comfort.
I have been planning upon so, looking forward to your views.

[Mr.Boss]

Originally Posted by Slickshift99

upsizing the front wheels by an inch or two, increasing width sayfrom 165 to 185 while letting the stock wheels be on the rear for comfort point of view.

Can be done, provided we have enough clearance with surrounding parts.

Rear wheels being non-steerable (except for cases with all wheel steering, again the articulation is very minimal) it is easy to accommodate wider wheels. Whereas on the front, many surrounding parts clearance to be checked.

[Turbohead]

Originally Posted by Slickshift99

Here my notion is, will the vice versa benefit as good on Fwd cars?
i.e. upsizing the front wheels by an inch or two, increasing width sayfrom 165 to 185 while letting the stock wheels be on the rear for comfort point of view. Thus offering greater performance and comfort.
I have been planning upon so, looking forward to your views.

Are you suggesting to increase the wheel (tire+ rim) diameter by two inches?

If you do so, the front portion of the car will be slightly higher and will mess with the aerodynamics of the car since it exposes the underside to direct winds. Your car will tend to 'float' at higher speeds and will return lower fuel efficiency due to drag

Ideally, just get a good pair of tires on all for corners. Sticking closer to manufacturer spec is the best in the long run.

[Kosfactor]

My Nano used to have a staggered setup, something to do with preventing the vehicle from over steering or maybe for packaging purpose they wanted a smaller wheel up front.

Anyhow, if the rear wheels did not have much to do in a FWD car, the manufacturers by now would have replaced it with caster wheels. So don't mess with it, use a performance tire if you are looking for more grip or else use normal road tires for comfort, fuel economy and durability. Same size on all four corners of course.

[GTO]

No manufacturer would put a fatter tyre on the front than the rear. Reasons:

1. Would look w-e-i-r-d!!

2. For 99.99% of car owners, understeer is easier to handle than oversteer. No brand would give the rear end lesser grip than the front. It's a recipe for disaster. As you rightly mentioned, many do give the rear more grip via fatter tyres, but never lesser.

[akshay4587]

The Only time you would benefit from a Staggered set up in a FWD car, is during a Drag race.
This is why you would see FWD Honda's having Fat Slicks at the front and thin tires at the back.
This is beneficial for extra traction, and for the reason, that the car only needs to travel in a straight line.
In real world, this will turn out to be disastrous.

[VKumar]

Originally Posted by GTO

understeer is easier to handle than oversteer. No brand would give the rear end lesser grip than the front. It's a recipe for disaster.

A few posts hit that particular quality threshold; that they appear probably once a week! Very well said GTO.

The staggered setup in FWD would have never looked weird if it had been the same from day 1 of car manufacturing. What looks good to us is decades of us being fed of that design language after all.

Long wheelbase (particularly the rear light >4m compact SUVs which we have), coupled with lesser grip at the back means, one enthusiastic turn and over steer comes into picture, there is some effect whose name I forgot, but it works like the front is pivoted. And how well people manage over steer? Well, either they turn turtle, or they counter steer to such an extent, that then they fish tail and over steer kicks in - in other direction. Better for manufacturers to play safe and either keep the rear grip heavy, or simply all round equal grip!

[TrackDay]

Like BHP-ian Mr.Boss said, you might need to factor in the wheel wells when you think about upsizing the front tyres. Not to mentions the sensors, ABS, ESC will go out for a toss. It would be like cutting a cat's whiskers off. The last thing you would want is a car with it's drive train and mechanisms fried out due to the strain. And yes, do forget about insurance in case of an unfortunate event

[Jeroen]

GTO is spot on. There is also another issue to consider. Power or rather torque. When your car has lots of it (eg BMW) rim size doesn’t do much.

But if you have an average car increasing the rim size on the driven wheel will get you less performance in terms of acceleration. Bigger rims require more torque. Top speed in theory could be a little higher, but in practice might be less too.

But the main criteria is the over-/understeer issue. And the fact you would like utterly ridiculous driving a set up like thay. Although the latter is in the eye of the beholder, obviously.

Jeroen

[longhorn]

For any front engined car (which is almost 99% of all cars nowadays), always install better, gripper tyres at the rear. Also, contrary to what most tyre showrooms advice, the newer tyres should always go to the rear.

The reason is simple. Since the engine sits in the front, the front tends to be heavier than the rear of the car. Due to this, we have more downward force acting on the front wheels at any given point of time. Thus, by default, the front wheels tend to be grippier as a norm. This is why, if running on bald tyres, the rear tends to lose grip if you suddenly hit a wet patch and make directional changes at the same time.

[vivekji05]

Slickshift99 has a point. A understeering front wheel drive is best set up with wider tyres at the front and slightly thinner ones at the rear.

Have experimented with this setup on one of my neutral handling cars and found it has a delicate balance which gets more playful when you are pushing it.

GTO
re: Staggered setup for FWD cars | Fatter tyres at the front?
No manufacturer would put a fatter tyre on the front than the rear. Reasons:

1. Would look w-e-i-r-d!!

2. For 99.99% of car owners, understeer is easier to handle than oversteer. No brand would give the rear end lesser grip than the front. It's a recipe for disaster. As you rightly mentioned, many do give the rear more grip via fatter tyres, but never lesser.

I am sure you forgot the Audi RS3 Sportback which has wider 8.5J rims and 255 section tyres at the front and narrower 8J rims at the rear wearing 235 section tyres.

[BloodyRaven]

Hi Slickshift99!

I would not recommend you to use a wider front tire in your car. Following are my reasons:
1. Vehicles use friction between the road and tires to move. The frictional force that helps a vehicle move is a function of two broad components - surface area in contact generally referred to as Contact Patch and Weight applied on each tire (this is different for the front and rear tires and also varies during acceleration, braking and turning). I have not considered material used for the tires for the sake of simplicity.

When manufacturers design tires for cars, they consider a lot of factors including:
a. Grip levels - The tire should not slip even in adverse conditions
b. Fuel efficiency - More Frictional force equates to higher rolling resistance and more fuel is used to push the vehicle forward
c. Ease of steering - A higher contact patch would lead to a heavier steering and needs to be factored in during the design phase

Now, consider increasing the width of the front tire. A broader tire will lead to 1. Higher grip levels (good) 2. Lower fuel efficiency (bad) 3. Slightly heavier steering (bad).

2. Secondly, I assume to fit a wider tire, you'd also need to use a wider rim. This would add more weight to the front and will have an impact on all the points a, b and c mentioned above. In addition to this, you'll be increasing the un-sprung weight of the car. Un-sprung weight is a cumulative weight of parts like suspension and wheels. Increasing the un-sprung weight would alter the suspension setup by a small margin and most definitely impact the handling of the car.

Having a wider rear tire in cars like the BMW 540d is done mostly to offer better grip levels. With so much power on tap, it is immensely important to have better control than to have the car sliding every time you accelerate.

However, this is my personal opinion and I am open to critical analysis of the points mentioned.

Cheers!

[carthick1000]

It is not a simple topic. Since your question concerns upsizing the front tire, let me keep the suspension kinematics out of play and only consider the influence of tire size. In reality, if you upsize the tire you have to also adjust your suspension kinematics to keep the car's steer behaviour the same to achieve the stable steering behaviour.

Most production cars are understeered by design.This is explicity chosen to err on the side of caution. Because an oversteered car can easily become unstable while cornering or any excessive changes to steering input (for eg. when trying to swerve to avoid an object).

If you don't modify the suspension kinematics and just increase the width of front tires alone in a FWD car the following things happen:

- Results in more contact patch for the front tires (than the rear)
- Increases the grip on the front tires more than that of the rear, depending on weight distribution and suspension kinematics.
- Makes your car become either neutral steer or oversteer depending on how much the width increase is (higher the more towards oversteer).
- Possible unstability in steer behaviour

So better stick to stock, if you don't know what you are doing.

Further reading (less technical) : http://racingcardynamics.com/understeer-and-oversteer/
Further reading (more technical) : https://www.amazon.in/Race-Car-Vehic.../dp/1560915269

Further watching: Understeer vs Oversteer: 4 part video series

https://youtu.be/lIUPYUjSNJI

https://youtu.be/MfPgKnxJJ6I

https://youtu.be/ysbPxjFaMug

https://youtu.be/CkRVls23478

[88_TANK_88]

Originally Posted by VKumar

Long wheelbase (particularly the rear light >4m compact SUVs which we have), coupled with lesser grip at the back means, one enthusiastic turn and over steer comes into picture, there is some effect whose name I forgot, but it works like the front is pivoted. And how well people manage over steer?

You are talking about lift-off oversteer. It happens when you are accelerating hard and then lift-off the accelerator pedal while starting to turn the fwd cars get loaded at front and with enough grip start to turn. But the rear becomes light and starts to lose traction, ie starts to drift without using the handbrake. The best way to counter is to start accelerating again with a hint of countersteer.
Cars like Gen1 Dezire (specially the diesel with heavier front) are quite prone to it as well.

[landcruiser123]

It'd look ridiculous. Besides, most (except legends like the Civic Type R) FWD cars are mass-market and designed to be cheap to manufacture. Having 4 tires of the same size gives manufacturers cost advantages.

Rear brakes help keep the car in line during braking, so no point in using thinner tires as it might result in over-steer.