While walking the dog this AM, I noticed that most cars seem to have 5 bolts per wheel, some have 4, and a few have 6. What determines the number of bolts? Why 5 as the standard? I presume it’s been that way for a while–my dad taught me to tighten 5 bolts in a star pattern when changing a tire; that was almost 30 years ago and it seemed pretty standard.
Fight my ignorance!
Wikipedia suggests that it has to do with the size of the tire and vehicle; bigger tires and cars have more bolts, which in turn suggests it is a compromise between cost and strength (more bolts = more expensive but stronger, although the cost of a bolt is surely a rounding error in the cost of a car). So for most cars, five is the optimum number but larger ones will have more (as many as eight) and smaller ones less (as few as three, which is the minimum number for stability).
The minimum is one; many high-performance vehicles have a single spinner nut in the center. 
As for “rounding error in the cost of a vehicle,” not so. I’d guess, very roughly, that going from four bolts to five, with no other change not necessary to make that happen, is on the order of $4-10 per vehicle. A $5 cost increase can make a production facility manager break down in sobbing convulsions; a dollar increase will result in a three-martini lunch.
But yes, it is 90% a physical load factor and 10% styling. Include in styling the fact that most American car buyers would freak out to find their car has only three wheel bolts, no matter how lightweight and unsporting it is. Further include in styling pickups with six and eight bolt hubs that will never experience any load heavier than a highway expansion strip.
Some lines of cars have both four and five-bolt wheels. The original Mustang had light-duty, four-bolt underpinnings on the six-cylinder models, and five on everything else. It’s a standard restoration upgrade to put five-bolt pieces in even without other changes. Also, years ago I was looking for a Honda Accord, and the salesman could tell from 200 feet, side-on, that a particular vehicle wasn’t the V6 I was asking about. Four-bangers had four lugs; V6s had five.
Thank you.
I was thinking more in terms of having bolts arranged around (but not at) the center; in that case, having just one bolt obviously wouldn’t work well and two would only have good support along one axis, like a table with one or two legs.
There was a time in my life when I had never really noticed that different cars had a different number of bolts on their wheels.
I first discovered that when I bought another car and stuck the spare tire from the old car into the trunk of my newer car.
Well, actually, I didn’t notice it even then. The day I had a flat tire while out on the road somewhere was the day I noticed. :smack:
[nitpick]
The lug nuts / lug bolts attach the wheel to the car. The tire stays on the wheel due to the compatible shape of these two - no fasteners needed.
[/nitpick]
Not only do the number of lug bolts vary but the spacing of the pattern does. Having a 5 bolt pattern wheel from one brand or model of car does not mean that that wheel will fit on another 5 bolt car from a different manufacturer.
Anyone else been reading the replies in a Michael Palin/Brother Maynard Cleric voice?
Yep. I’ve got about a dozen cars with this setup. All’s ya need is a brass hammer!
It’s not even sufficient to have the same bolt pattern. Last year I bought a set of used snow tires. I pick the particular set I bought because they were on wheels with the same bolt pattern as my car. I installed the wheels, set the air pressure, replaced the hub caps, hopped in the car and tried to drive away. The car wouldn’t move because the brake calipers hit the inside of the wheels.
The only car I can remember that had three lug nuts per wheel was Renault’s Le Car. 
Dem nuts dem nuts dem lug nuts,
Dem nuts dem nuts dem lug nuts,
Dem nuts dem nuts dem lug nuts,
Hear the word of the Lord!
NEVER use a hard-metal hammer on spinners, ever. Never use a rubber one to tighten a spinner.
Lead. Hard to find these days, but a lead hammer is the only safe tool to tighten spinners. They are essentially foolproof, because if you over-exert you simply dent the lead facing more deeply. Even brass will apply excessive force and jam or break a spinner.
I’ve had many discussions with British car buffs who are certain they know how much force to apply with a brass hammer. Maybe with a great deal of experience, yes, but it’s easy to apply too much and break a lug, crack the nut, or jam it. I’ve spent time helping them get a jammed nut loose, too.
Lead.
…and we still haven’t gotten to the wheel and tire diameter, width, or total offset. Having the same number of holes is only the beginning.
That was a long ass walk too…:mad:
Then there’s the Chysler/Dodge/Plymouths from the early 60s where the lug nuts tightened in opposite directions on either side of the car.
There’s also the matter of different wheels for the same car requiring different lug nuts because of the bevel of the mounting holes. I think there are at least three common variations.
Some things become more difficult the more you know.
My first car (1968 Plymouth Satellite) had reverse threads on the drivers side. Each lug had an L stamped on it.
The Smart FourTwo has 3 bolts per wheel.
Something I’ve noticed on my last two cars is that they use bolts instead of nuts. On my older cars the studs would be attached to the hub and you could hang the wheel on them then put on the nuts. Now I have bolts so have to hold the wheel to the hub and get one bolt started which is very awkward. Is there any advantage to bolts over nuts?
It’s funny. I’ve never given any thought about one lug wheels and what are apparently called “spinners”. But that photo instantly puts the theme song for Speed Racer in my head. And there it is, except that it has three wings or whatever.
