[McLaren Rulez]

I've been wondering about this. What is the advantage having five lug nuts on the wheels instead of the normal four? I saw a Fortuner the other day and it had six! So how exactly do the extra lug nuts help? Sure, if you lose/damage some lug nuts, then the more you have, the better. But other than that, are there any benefits to having more lug nuts?

[Shan2nu]

I guess having more lug nuts distributes the force more evenly and reduces the load on each nut. A circular table with 6 legs is more stable than one with 5, 4 or 3.

Shan2nu

[Nikhilb2008]

And this is truer for bigger, heavier vehicles.

The Nano manages with 3.

Most cars like the Swift, Spark, 800, Alto, Wagon R, Esteem, Baleno, Getz, Verna, Lancer, Cedia, Corolla(old), have 4.

Civic, Innova, Laura, Mercs, Beemers, etc have 5. Usually it's a 5-hole 114.3 PCD config. The Germans are a 112 PCD config.

Safari, Scorpio, etc have a 5 hole 160 PCD. The larger PCD helps in distributing the heavier vehicle load evenly I guess.

So, you see from the above, the heavier and bigger a vehicle gets, the more lug nuts it has and in some cases, a bigger PCD.

[Mpower]

& F1 cars have only 1.

[pradipk]

Originally Posted by Mpower

& F1 cars have only 1.

The "Feather Weight" vehicle on the planet.

[vigsom]

as far as I know,the number of lug nuts n bolts depends on:

• rim diameter
• load carrying capacity of wheel

[rohan_iitr]

Originally Posted by Mpower

& F1 cars have only 1.

That is to minimise the time taken to change the tyre during a race.

Rohan

[Mpower]

Originally Posted by pradipk

The "Feather Weight" vehicle on the planet.

when its standing still. On the move there is a ton (pun not intended) of downforce.

note that it can also pull 6g of lateral load

[clevermax]

Those Volvo buses have more than 6 on each wheels!

[Nikhilb2008]

Originally Posted by Mpower

when its standing still. On the move there is a ton (pun not intended) of downforce.

note that it can also pull 6g of lateral load

Then how can they manage with only one? I mean, is it just because of the high tech, strong materials used in the construction or is there something else?

[khoj]

Originally Posted by Mpower

when its standing still. On the move there is a ton (pun not intended) of downforce.

note that it can also pull 6g of lateral load

The materials of construction along with the size of that one nut allow the loads to be evenly distributed over the large cross sectional area. The nuts are torqued to approx 500lb/ft each and to ensure that the nuts do not work themselves loose when the wheels are turning the right hand side of the car uses right-handed threads, the left-hand side of the car left-sided threads.

Edit : Found something related and interesting
http://www.autoevolution.com/news/fe...ges-17062.html

[Rehaan]

Originally Posted by pradipk

The "Feather Weight" vehicle on the planet.

Its not just F1 cars that use this system. Look at LeMans cars - they use em too. Primary purpose is to speed up tyre changes, though weight savings might also play in its favour depending on construction and materials used.

But why not WRC ?? I guess simply because tyre-change times aren't as important here. (Probably also due to the rules).

On the other hand, there are some "road cars" that use this system too. Take for example the Bugatti EB110 and the Porsche Carrera GT :


(Red wheel nuts on the LHS, blue on the RHS. Each with threads going in a different direction so as not to undo themselves)

And this isn't some "new technology concept" either. Vintage race cars have used single wheel nuts since many years ago.

Originally Posted by vigsom

as far as I know,the number of lug nuts n bolts depends on:

• rim diameter
• load carrying capacity of wheel

One more factor could be redundancy! Gets scary on cars like the nano with only 3 nuts!

Originally Posted by Nikhilb2008

Then how can they manage with only one? I mean, is it just because of the high tech, strong materials used in the construction or is there something else?

In addition to materials, its also about the way the load is spread (simple physics, instead of material properties).

Instead of using four smaller bolts to fasten something, you could use a single larger dia (hollow?) bolt which could give you the same strength and load bearing.

The principle applies similarly in a lot of other areas. Eg. Tube frame vs Ladder chassis / table with 4 thin legs vs large central post.

As for spreading the load when a single bolt is used; the bolt is just in tension, its the mounting surface that will probably still be large enough to handle cornering forces and such.

Originally Posted by khoj

...large cross sectional area...

^ This is key.

As vigsom said, each bolt can only handle a certain amount of forces based on its diameter. The more force the wheel has to deal with (weight or high-performance driving forces) requires there to be more bolts. Alternatively, larger diameter bolts could be used but that would be less practical than just adding one more bolt.

cya
R

PS - i guess i am saying "bolts" when i should be saying "studs"?

[Rehaan]

Originally Posted by Rehaan

Its not just F1 cars that use this system. Look at LeMans cars - they use em too. Primary purpose is to speed up tyre changes, though weight savings might also play in its favour depending on construction and materials used.

Unlike the majority of a Formula One car's parts, the manufacture of the wheel nut does not have to be a particularly scientific process. Machined in conventional fashion from a block of steel, Jordan have used the same simple nut design since 1997.
Source (Its an article from 2003, so don't know how true it stands today)

Originally Posted by Rehaan

And this isn't some "new technology concept" either. Vintage race cars have used single wheel nuts since many years ago.

Here you go. A Bugatti from the 1920s :


Source

^ Check out the ALLOYS as well!

cya
R

[Mpower]

Originally Posted by Nikhilb2008

Then how can they manage with only one? I mean, is it just because of the high tech, strong materials used in the construction or is there something else?

Its sole purpose is for quick pitstops. Having 5 fasteners is optimum to get a good clamp load. Like someone said, the torque is 5 times higher.

I've also seen racing conversion kits where you replace 5 lugs with one center nut. They replace lugs with dowel pins for piloting and anti rotate feature.

[Crazygoan]

Hi...not sure if I'm on the right thread, but I want to change the lug nuts on my Chevy Cruze LTZ AT. Do I use 12x1.25 or 12x1.5? Please advice. Thanks!