(Submitted by Keith B.) So seriously, what the heck is the story here? Wheel bolt patterns for passenger cars and light trucks have been pretty consistent over the past sixty years or so. 4 lug, 5 lug, and 8 lug are especially popular configurations. 6 bolt patterns seem to have become increasingly popular in recent years as well; I think the first vehicles I noticed them on were compact Japanese pickups (Nissan, Toyota, etc). GM also went to a 6 lug on their half ton trucks sometime in the 80’s I believe. But 7 lug wheels?
In 1997, Ford decided to get creative. With the release of their new F-150, Ford began the process of creating two separate platforms for their light duty trucks. With the Super Duty trucks a couple of years away, the ¾ ton and 1 ton models were still based on the age old platform that was first produced for the 1980 model year.
And this is where things get a little strange. Alongside the newly redesigned F-150, there was a new “light duty” F-250. This truck was badged as simply the F-250, while the older design ¾ ton got new badges that specified it as a “Heavy Duty” F-250. This makes it really easy to tell if an F-250 of that generation is a ’97 or ’98 model. Simply look for the model badges that say “Heavy Duty” on them. Prior to 1997, there was no need to call it Heavy Duty, since there was only one F-250 in the lineup. The heavy duty F-250 came with 8 lugs, along with a full floating rear axle and was available with the Power Stroke diesel.
Anyway, back to the newly created “Light Duty” F-250. The most interesting detail to me on these trucks is the odd-looking 7-lug wheel bolt pattern. Why 7-lugs? Seriously, why?
I suppose it was an effort to convey the extra strength and capacity of the F-250 over the F-150 (5 lugs), but also to show that it wasn’t quite as tough as the Heavy Duty F-250 (8 lugs). They may have also wanted to show superiority over competitors’ trucks that had “only” 6 lugs.
Seriously though, creating a unique bolt pattern for one vehicle in Ford’s extensive lineup seems a bit, well stupid to me. I’m sure the aftermarket wheel manufacturers were cursing under their breath as well.
During this same time period, the choice of wheel lug patterns between manufacturers was all over the place. As far as half ton (or light duty ¾ ton) pickups went, Ford was running both 5 and 7, Dodge ran 5, Chevy and Toyota ran 6. Nissan and Toyota were also running 6 on their small pickups.
Then, in 2004 when Ford brought out the next generation F150, they switched over to 6 lugs. I don’t believe there was a light duty ¾ ton. If you upgraded, you went right into the Super Duty series of pickups. Interestingly enough, Toyota switched to a 5 lug pattern for the fullsize Tundra in 2007, though the smaller Tacoma stayed with 6.
So, dear readers, what do you think? Was the 7 lug concept purely a marketing idea or was it some engineer’s brilliant idea?
Marketing. Ford has been doing this since (at least) the first Mustang. If you got an I-6, you got 4 lugs. If you got a V-8, you got 5.
Even with the K-code 271 (gross) horsepower engine, I highly doubt there was enough torque that you could snap off studs if you only had 4 of them.
Fox Mustangs had 4 lugs no matter what, IIRC.
That’s not entirely correct. The Mustang SVO had 5-lug wheels.
1993 Cobra R too
Now that I realize that I think that is a bad idea since it makes it hard to get additional rims if need be. I am still a wee bit surprised FoMoCo split the F-150 from the heavier duty trucks.
Why? F150’s are very mainstream–Super Duty’s are real work trucks–they don’t share any chassis parts.
I remember worrying if four lugs was enough the first time I saw that configuration. Then, in Europe in the ’70s there were 2CVs. Wonder if the wheels had speed ratings? It didn’t pass me by that certain cars (like my present Cinquecento) have a single bolt holding the hubcap in place, which, if you didn’t know better, might appear to hold the entire wheel assembly together.
It would not be impossible for some marketing departments to insist on a 7 bump hubcap over a 6 lug wheel…. did you check? LOL.
Later Citroens like my Xsara the hubcap bolts on with the wheel lugs no chance what so ever of them coming off when you hurl it into a corner too fast.
The 4th gen (1990-93) Honda Accords had the same setup. On the DX and LX models with full wheel covers, the wheel cover slid onto the studs *before* you attached the lug nuts. Worked quite well, though replacing a damaged one could be a pain.
Peugeot 404s had three lug wheels, and were routinely overloaded.
Back in the day, couldn’t you repack the front wheel bearings or replace brake shoes on lots of cars just by popping off the grease fitting, removing the cotter pin and castle nut, then just wiggling the whole wheel and drum off as one assembly? Hub caps under the lug nuts would prevent that.
Smart cars only have three lugs as well. I think this is amusing since even my buddy’s 4 wheeler has fout
The 3 bolt wheel configuration was popular with the French through the latter half of the 20th century.
Off the top of my head, the Renault 5/LeCar, Citroen AX & Visa, certain versions of the lovely Alpine A310 all ran 3 bolt wheels. The last one I’m aware of is the Peugeot 106, which was in production until 2004. The cooking models had 3, the sportier versions ran 4.
As mentioned by others, the current Smart runs 3. This may be the only 3 bolt wheel car in prodcution at the moment. Unless anyone knows of others.
Many supercars run racing-style single bolt wheels.
My Citroen ID19 only had 1 (one) lug nut.
Of course it was holding the wheel onto a hexagonal hub so it only had to deal with side thrust rather then shear.
I think it was indigestion. I am a little confused on the chevy. My dad and I each had late sixties pickups with six lug. It would fit on a seventy something Nissan (Datsun) then the Nissan hub became too big. I think they all have indigestion and so do I when I try to save a few bucks moving wheels around. I don’t know when chevy went to five lug.
My stomach still calms some when I look at my old trailers that share wheels.
GM (10 series) Went to five larger lugs when they first installed front disc brakes for the 1971 model year. By the 1990’s, 2wd 1500’s still had five, but the 4×4’s and 2500’s below 8500GVWR (light duty in Ford and EPA terminology) had six.
I’m sure it all made engineering sense. Five up to about 6000lb GVWR, six up to 7500 and eight above that. With the huge numbers of these trucks produced over the years, additional parts commonality probably would not have reduced costs any more than the already were.
Then with the ’99’s, GM went back to a six-lug pattern that remains today. But ’71-’98 2wd Half-ton pickups got five lugs.
I don’t know if this response is BS, or brilliance:
Ford was so tramatized by the market backlash to their endless stream of el cheapo mobiles in the late ’70s and early ’80s that featured crappy looking 4 bolt wheels on anything below a full size car, that their decision to build something that people would actually want to buy included a return to a 5 bolt pattern to improve style and substance. Once the discovery was made that something above the lowest common denominator helped sales, maybe they went a little overboard.
4 stud wheels on Falcons disappeared early on down under whether it was the fault of the wheels or the underdone engineering they were bolted to the 5 stud running gear didnt fail as easy as the weaker 4 stud system did, NZ got Falcons from Canada and Aussie and the lack of wheel studs made it easy to tell them apart.
I honestly never knew these existed. Since you only showed pics of the wheels with a center cap installed, my suspicion was that it was just the center cap with 7 fake lugs, to go along with the 7-spoke wheels.
I googled and saw pics of the brake rotors with 7 studs though. I bet there were some Ford owners upset because their options were limited if they wanted to swap-in aftermarket wheels.
Ford’s way to showcase their engineering prowess. It’s cheap and easy and yes cheap. it’s the Ford way.
That ain’t half of it. Looking up rotors and drums for late 90’s F150’s and F250’s are a nightmare. 5 Bolt wheels can be 12mm or 14mm, 4WD or 2WD, disc or drum on the back–7 bolts are even listed for F150’s. Now add in the years Ford sold old model F150’s as Heritage models as price leaders and it gets really confusing.
Trying to get the right part for a customer involves asking questions but most guys want to argue–If I had a nickle for every smartass thats told me “what do you need to know that for–they are all the same, do you need to know the colour too?”
The F250 LD was short lived as a name plate, the truck lived on as the F150 7700 to denote the increased GVW over a 5 lug F150.
The whole idea behind the different patterns is to prevent someone from swapping on tires and more importantly wheels that are designed for the rated load. Leave it 5 Lug and run the risk of people putting on wheels that aren’t strong enough. Give the 250 LD/ 150 7700 8 lugs and people will think it is a real truck and believe it can keep up with its tires. I’m sure the lawyers had something to say about the mess.
Wasnt it Ford that came up with weird wheel and tire sizes on the EXP and maybe other cars in the 1980’s?
Edit: Found the reference. It was the Michelin TRX.
https://www.curbsideclassic.com/automotive-histories/automotive-history-michelins-trx-tire-reinventing-the-radial-tire-didnt-work-as-well-as-inventing-it/
At one point there was a good reason to have a different lug count. Back in the early 1970s 3/4 and 1 ton trucks began using tubeless tires in place of the old tube types. The difference in the wheels between tube and tubeless were in the slope of the rim at the bead seats. Tube rims had a 5 degree slope to the seat and tubeless were 15 degrees.
In order to differentiate the tubeless tires used 16.5 inch rims and tube tires were 16 inch. This turned out to be disasterous for many tire techs and DIYers. Due to the taper in the 16.5 inch rims, a 15 degree 16.5 inch rim was actually smaller in the outside diameter than a 5 degree 16 inch rim. The 16 inch tire would fit over the 16.5 inch rim. It could not be seated because the rim was larger in circumference at the bead seat. People would inflate the 16 on a 16.5 rim but it wouldn’t make the telltale “Pop” indicating seating. They added more air and the beads could break causing an explosion with incredible force. Many lost fingers, hands and some were killed.
One of the great problems was that it was very difficult to tell the difference between a 16 and 16.5 inch rim without a marked tire on it. The other was that the rims were interchangable on the same vehicle so it was not uncommon to have one truck with 16s on the front and 16.5s on the back, especially as the trucks aged.
One of the original suggestions for avoiding this was to have a different lug pattern for 16s and 16.5s so the only size wheel that could be used would be the one the vehicle came with. This was rejected for cost considerations.
Many years ago, I litigated a case of 16/16.5 mismatch on a GM 3/4 ton van where the new owner of a $500 ’78 GMC Van looked at the left front tire on his truck at the tire store and bought 4 – 16 inch tires. The tires on the truck were old and curb damaged and the markings on the sidewall were unreadable. The rear rims were 16.5s and when he tried to air up the 16 inch tire, the bead broke and the tire exploded launching the rim and tire 16 feet up and taking 3 og the guy’s fingers and destroying his hand. Thankfully, the man’s teenage son who was helping him, wasn’t injured.
There was a lot of this litigation from the ’70s to the late ’90s.
Interesting, an example of how tort law explains otherwise baffling things. You’d think there’d be an SAE white paper on this issue if it was really a tradeoff in mechanical engineering.
Logistics is another reason: militaries deliberately lie about certain artillery bores to keep soldiers from confusing incompatible rounds of the same diameter. Hence, 23mm vs. 20mm. This could make a difference in the Fog of War.
Sometime in the 80’s or later trucks went back to 16 inch rims. Its getting hard to find 16.5 inch tires for trucks from that era.
16.5″ wheels were “split rim” types. Split rim wheels were known to blow off even with the proper tire. They were supposed to be inflated in a safety cage. Since the design was not airtight, tubeless tires could not be mounted. That is the reason for 16″ wheels. Those were airtight and tubeless tires were the intended use.
Not all 16.5″ wheels were split-rim. We had a 1973 and a 1979 3/4T Chevy that came with 16.5″ wheels stock.
no 16.5 was split rim as these were tubless tires-
The “light duty” F250 still exists, except they call it the F150 with the HD payload package. This is the truck that Ford always quotes for the high F-150 payload in there ads. Very few trucks seem to be actually sold with this package and there is a lot of restrictions to actually get it. This option package still uses the ridiculous 7 bolt wheels. IMO, the 7 lug wheels serve no purpose whatsoever. Ford should have either kept with the 6 lug F-150 or gone to the same wheel as a F-250 Super Duty. I wouldn’t want to own a truck with those wheels and have to try to find a replacement or get some steel winter wheels.
The F-250 used in the 1997 generation Ford trucks was nothing new. Ford did this before when they still marketed the F-100 trucks. The F-150 was a step up, a “heavy half ton” or light duty 3/4 ton. These were basically 1/2 tons with higher payloads and GVWRs. GM also did this with the 2500 trucks, which were basically half ton chassis with HD springs. They also offered a 2500 with C6P HD chassis (same as 1 ton) later becoming the 2500 HD.
Yep, my in-laws have a 2009 F-150HD with the 7 bolt wheels. Long box (8 foot) extended cab. It’s an odd ball, but serves them well for pulling a goose neck cattle trailer and a 5th wheel camper.
The “heavy half” was invented due to EPA regulations. Before that, 5600lb was the typical GVWR of a Dodge D-100, Ford F-100 or GM C-10. The “3/4 Ton” was typically 7500lb GVWR.
Passenger car emissions standards were raised to 6000lb GVWR, so the F-150, C-15 and others were marketed at over 6000. Later, it was raised to 8500lb GVWR, hence the “Heavy Duty” 8501lb or higher GVWR “3/4 ton” pickups we see today.
If you really want to see some funny lugnut deception, look at the pentagonal outline with 5 circular corners on Rover 800 (Sterling 825/827 in the US) that cover a 4-lug square bolt pattern.
The F-250 thing was probably to make sure that F-150 parts couldn’t be too easily substituted for a repair that they would be insufficient to handle. Not a terrible idea, but less than convenient.
Here’s a pic of the Sterling ones.
I’m not much of a truck guy but have noticed how the F-250 has more lugs than the F-150 and higher up (F-350?) they stick out to the sides.
On cars though I have a pet peeve and that’s when 4 lugs are used where there should be 5, like on any V8 or wheel diameter above 15″.
The 7 lug pattern could be ordered as a part of the 7700 package on the F-150 of this generation. I worked at a used car lot one summer and we had one of those in. It didn’t have many options, and was a basic work truck that was meant to haul heavy loads. My parents had a contractor who had a 97 F-250 with the seven bolt pattern, and he replaced it with an 04 or so F-150 with the seven lug pattern.
The GM full-size trucks had 5 lugs for 2wd, and 6 for 4wd for the 1500 models. The 2500 and up all had 8 lug wheels. When they went to the GMT800s in 1999, they became 6 lug or 8 lug.
The Chevy Colorado and GMC Canyon use 6 lugs on most models, and the work trucks seem to only have 5 lugs.
The 7700 package was what the F-250LD became known as after the Super Duty debuted in ’99. The only difference was the badge on the tailgate…..
So many questions with 7 though – 3,4,5,6 and 8 all divide evenly into 360 degrees. But 7 does not. How is the spacing configured – do they just get it “close enough” to even where it doesn’t matter?
Computers have made it perfect without fitting the human compatible numbers.
Here. Took yesterday
I bought a used ’97 ‘light duty’ F-250 in 1999. It was identical to your lead photo green/silver truck, except mine didn’t have 4WD. I used it to tow a 23′ travel trailer. Great truck. Had those same chromed steel wheels pictured. I didn’t particularly care for them, so I checked on A/M alloy wheels – found exactly ONE kind of wheel that you could get in the 7 hole bolt pattern. Didn’t like those, either.
The original non-Super Duty light F-250 used the oddball 7 lug wheels, sometime later the same truck was re-named the F-150 7700. They were very little more than bigger wheels and higher capacity rear axle on an F-150. Still basically a 1/2 ton, they did not hold up well in commercial applications. The 16″ wheels were unique (shades of the 390mm wheel) but at least didn’t use a strange tire. A very interesting ‘feature’ was though the F-250/150 7700 did have 7 lug nuts, the stud diameter was actually smaller than the regular F-150’s 5 lug studs. By the time these trucks came out, the 16.5″ wheel was long gone on Ford trucks, so I doubt the reason was to differentiate between 16″ and 16.5″ wheels. I never saw a point to it.
Marketing. It’s an omnipresent force.
Another interesting thing I remember is the wheels on these trucks were a “hub-centric” design, meaning they did not rely on the lugnuts to center them. Rather, the center hole of the wheel fit precisely on the hub of the axle flange or brake rotor and the lug nuts were flat faced with an integral washer. Unnecessary over-engineering in my opinion. Does the latest generation of F-series still have this? Or any other vehicle for that matter?
My 2000 4Runner had hub-centric wheels. Dang near impossible at the time to balance, nobody had the right equipment and few people understood the difference. I don’t know of any advantage to the design, but there was sure a large downside.
Isuzu’s truck-based consumer vehicles (Rodeo, Trooper, Pickup, Amigo) all used the 6X139.7mm bolt pattern, same as Toyota, Nissan, and some others. Since they are lug-centric, you can’t just grab a Toyota wheel with the same pattern and throw it on there.
“6 bolt patterns seem to have become increasingly popular in recent years as well; I think the first vehicles I noticed them on were compact Japanese pickups (Nissan, Toyota, etc).”
I can’t speak for Nissan but small Toyota pickups in the 80’s are 5-lug; the 4wd versions were six.
My 1941 Chevrolet car had 6-lug rims on it. They have been around for a long time.
Seems five lug is the most popular. Jeeps and Land Rovers and Mercs are all five. Been kinda fascinated by lug patterns after reading a CC article a little while back. and realized I had never really noticed all of the different patterns. The only car that I’ve noticed with three lugs is a Smart but I have never noticed seven. The 80 series land cruisers were six but now the 100 and 200 are five while the 4Runners are still six. The GM trailblazers were six and so are the Acadias but all the minvans tend to be five. Gm seems to like the six on its light duty lines. Saw an older Econoline with six the other day but normally I’ve noticed eight (diesel or gas). I thought maybe it had to do with engine torque. The more power to the wheels required more lugs to distribute that turning power more evenly. I’ve turned into a lug nut. I count lugs like a mad man on the street.
My Kia Sedona may be the only minivan with six lug wheels. I have never noticed another.
No, many of the post 2005 GM U body (Uplander, Montana SV6, Terraza, Relay) vans have/had six lugs. Particularly the AWD models. But I’d noticed some of the FWD versions had them too, I think it was in preparation for the release of the Traverse/Enclave/Outlook, which are all six lug.
” I thought maybe it had to do with engine torque. The more power to the wheels required more lugs to distribute that turning power more evenly.”
Yes, in slightly different way.
There is a lot of quite understandable confusion on how threaded fasteners work, particularly in the case of wheel lugs. While one might logically think that the load is carried in shear (sideways), that is not the case here. What is really happening is that the wheel and hub are clamped together sufficiently to act as one piece. The clamping force is called preload. Lugs are in tension due to the tightening torque in order to accomplish this. That is one reason under-tightening is such a bad idea. The engineer selects the number and diameter of lugs based on predicted loads and the design of the hub and wheel itself.
Thanks!
In the (very small) window of time when my uncle owned a Smart, my sister a Focus, and we still had the F-250 LD, there were occasions when all six lug-nut numbers were present at our arm.
3-lug: Smart
4-lug: Focus
5-lug: Kia Sportage, Mazda Tribute
6-lug: F-150
7-lug: F-250 LD
8-lug: F-350
Attention, anyone who cares: I just checked, and the new 2015 F-150 will no longer offer 7-lug wheels on its HD Payload Package, but rather just heavier-built 6-lug rims. That’s probably a good thing for those that want to swap out the wheels, but I wonder if it’ll lead to someone mounting P tires on something that’s legally supposed to have LT tires.
Not only tires but aftermarket wheels that aren’t up to the task. Many tire stores don’t pay attention to that kind of thing when they sell wheels. A friend of mine bought a Suburban 1500 and when we had the wheels off to do the brakes I noticed that they were rated for only 1250lbs ea. The truck required a minimum of 235/75-15XL tires which are rated for around 1700lbs. He quickly replaced them with some factory rally wheels.
I did find one honest wheel salesman at Four Wheel Parts in Redondo Beach. When looking at aftermarket wheels for the ’94 F-150 he saw that I actually used the truck to carry payload and advised me to stay with the stock steel rims. He pointed out the thickness of steel, stock vs. his aftermarket ones.
Now that I know they exist, I am making it my personal mission to find a current generation F-150 with the 7-lug wheels
From 2004-10, all HD F-150s used 7-lug steelies that were outwardly identical to the standard 5-lugs. Only after removing the hubcap could you tell the difference. All SuperCab/8′ bed F-150s were automatically HDs, and it was only available as a SuperCab/8′ or Regular Cab/8′. Starting in 2011 with the new engines, aluminum 7-lugs were made standard on XLTs and optional on XLs. (Standard XL rims were still the steelies.) Also new for 2011 was the ability to get a SuperCab/8′ F-150 _without_ the HD package for the first time since 2003 (although every 2011+ SuperCab/8′ F-150 I’ve seen has been an HD). New for 2012, the HD package was expanded to SuperCrew/6.5′ bed models. I’ve seen two of those in the past 2 years, and one was in California.
In short, what I’m saying is good luck. It’s hard to find, mostly because the HD package is such a niche product. The guys that wanna tow 10K+ lbs. regularly are more apt to get a 3/4 ton.
I got a 2003 F-150 with the 7700 heavy duty towing package. It also had the 7 lug configuration and is reflected in the hubcap. So this oddity reached down to the F-150s as well.
The F-150 7700 Package from 2000-03 was the F-250 light duty; they just changed the name. Mechanically identical, the only way to tell a ’99 F-250 LD and an ’00-03 F-150 7700 apart is the badge on the tailgate
The 7700 package is not a heavy duty towing package it is a high payload package. Now you can get max towing on a F150 7700 but the presence of a 7700 badge does not mean that it is set up for towing large loads.
Lots of confusion @ FoMoCo re: wheels. Add to that a change fr 8×6.5 (165mm) in lug pattern to 8x170mm around 1997 – ’98. Seriously Ford? A 5mm difference???
It was dumber than dirt! Now ya can’t find the dang things as they rot out!