Why different # of studs on wheels - cars, trucks..

[Chris.m]

This is just a general question that popped up in my mind.

A quick google search turned up nothing.


Why do vehicles have a different number of studs/ bolts on the wheels?


Smart cars have 3, older Honda civics have 4, lots of cars and cross-overs have 5, and it seems anything on a truck platform has 6. Some really heavy-duty trucks have 10.

Theory 1 Weight

Is it just for shear-strength? Maybe a vehicle that weighs more needs more? But a 5800 pound Rolls Royce only has 5... My 4500 pound Pathfinder has 6...

Although isn't most of the downward force exerted by the weight of the vehicle being countered by the friction between the rim and disk/drum instead of being pushed on the studs themselves? So in this way, the studs and lug nuts are just providing pressure?

Theory 2 Torque

I almost thought that with more torque produced, more studs/bolts would be required, but look at the Mercedes Cl55 AMG with 516 ft/lb at 2750 rpm with only 5 bolts... My 265 ft/lb @ 3200 rpm pathfinder has 6...

This has got me stumped.

[Dattebayo]

Why do they make hot dogs in packages of 6 and 10 when the buns come in packs of 8?

And other odd ball questions in the universe.

[Red coupe]

Cars have different numbers of studs because engineers specify different numbers of studs...

Its cheaper to do less... its technically lighter too, but meh... mostly cheaper.

Its stronger to do more. At some point it is overkill... Choose somewhere in between based on your needs and budget... 4 and five lug seems to work out well for passenger type cars... Heavier vehicles or vehicles that are able to produce higher loads at the wheels may need more.
They also pick the material the stud is made from..

[Chris.m]

Cars have different numbers of studs because engineers specify different numbers of studs...

Its cheaper to do less... its technically lighter too, but meh... mostly cheaper.

Its stronger to do more. At some point it is overkill... Choose somewhere in between based on your needs and budget... 4 and five lug seems to work out well for passenger type cars... Heavier vehicles or vehicles that are able to produce higher loads at the wheels may need more.
They also pick the material the stud is made from..

Thanks for the logical responce.

Although it is somehow isn't satisfying

I guess I was expecting something magical.

It just seemed strange that it would appear the number of studs were chosen based on class of vehicle rather than specs...

I guess 10 bolt Ferrari rims wouldn't look so hot either....

[IanS]

Many ferrari wheels are center lock, one giant nut.

Other odd questions, why do drive through atms have braile on the keys? lol

[Chris.m]

Other odd questions, why do drive through atms have braile on the keys? lol

I was just about to answer that it is cheaper to make all atm keypads the same - then I got thinking. Why would they have braile on the keys at all? They wouldn't be able to see the screen anyways....hmmm

[Ron Burgundy]

You can't drive your blind buddy to take out some cash?!

...and I believe there is some sort of audio assist option at all ATMS.

[MinisterofDOOM]

There's more to it than just "more lugs=stronger" too. Overall diameter of the lug pattern is important as well, as is the thickness of the lug bolts.

For instance: Frontier, Tacoma, and their SUV brethren are 6 lug (share the same pattern, in fact). But half-ton Dodges are 5 lug. The Ram lug pattern is more than an inch larger in diameter than the little Japanese truck pattern.
Chevy's got a 6-lug setup that's the same diameter as Dodge's 5-lug on their half-ton.
And Ford's half-ton 5-lug setup is actually compatible with Nissan CARS, it's 5x114.3, same diameter as the Nissan truck setup. Ford also does a 5.5'' (same as Dodge/Chevy) on some half-tons, though.
And, bizarrely, Ford also uses a SEVEN lug setup on some F150s and 90s "pre-HD" F250s.

Although isn't most of the downward force exerted by the weight of the vehicle being countered by the friction between the rim and disk/drum instead of being pushed on the studs themselves? So in this way, the studs and lug nuts are just providing pressure?

That depends on the car. Nissans are "hub-centric" and have a lip on the hub that's designed to bear much of the load. It also makes mounting wheels easier.
Some other brands are not hub-centric.
Mercedes actually does not use lug NUTS. You remove the whole lug bolt from the hub. Mounting wheels on MB cars is obnoxiously, unnecessarily difficult because you almost need 3 hands: two to hold the wheel in place and one to insert the bolt.

Many ferrari wheels are center lock, one giant nut.

E-type Jags and a lot of other sports cars from the era were, too. Thread direction is reversed on each side to prevent reversing while driving due to wheel rotation.

Weird lug trivia: Camry has always been 5-lug. Most of its competition was 4-lug until the early 2000s. Even the Maxima was 4-lug in the 80s. Altima didn't go 5-lug until 2002.

[IanS]

That depends on the car. Nissans are "hub-centric" and have a lip on the hub that's designed to bear much of the load. It also makes mounting wheels easier.
Some other brands are not hub-centric.
Mercedes actually does not use lug NUTS. You remove the whole lug bolt from the hub. Mounting wheels on MB cars is obnoxiously, unnecessarily difficult because you almost need 3 hands: two to hold the wheel in place and one to insert the bolt.

As far as I know, all modern factory wheels are hub centeric. only aftermarkets are often not.

Its not just Mercedes using lug studs, all BMWs and volkswagons do as well, not to mention all Audis, and most saabs and volvos. even ford used lug studs on a few cars, so does Hyudai/kia.

[szh]

Other odd questions, why do drive through atms have braile on the keys? lol

I was just about to answer that it is cheaper to make all atm keypads the same - then I got thinking. Why would they have braile on the keys at all? They wouldn't be able to see the screen anyways....hmmm

Some ATM's have plug-in jacks for audio devices for blind folks. So, in theory, a braille keypad would make sense for them.

However, it still seems quite unlikely that either an audio jack or a braille keypad gets used very much.

Z

[Chris.m]

Well now I know..

Thanks for the responces; I knew you old guys would amaze me with your knowledge of lug nuts

[Dattebayo]

I knew you old guys would amaze me with your knowledge of nuts

Yep.

[krash]

Its not just Mercedes using lug studs, all BMWs and volkswagons do as well, not to mention all Audis, and most saabs and volvos. even ford used lug studs on a few cars, so does Hyudai/kia.

Thats probably the only thing I hated about my 850 turbo. I really miss that car

Well now I know..

Thanks for the responces; I knew you old guys would amaze me with your knowledge of lug nuts

We spend a lot of time learning about nuts here on NICO.

[IanS]

Well now I know..

Thanks for the responces; I knew you old guys would amaze me with your knowledge of lug nuts

Hey don't call me old.

BRB, gotta go yell at the kids playing in my yard again. Darn children having fun and stuff.