Questions About Your Imperial's Wheel Lug Nuts, Bolts & Bolt Patterns

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From Pete:

1970 was the last year for LH thread lug nuts on the RH side of the car. For 1971 all lug nuts were RH thread. Although I have worked on these cars for over 20 years, I screwed up when trying to remove a RH wheel on a 65 Polara this past weekend. I'm busting my guts to crack the first nut loose and trying to figure out why it's so tight. Then -- DOH!!! -- the source of the "problem" dawns on me.

Question from Mark:

Can someone explain this to me again? I always forget. On the driver's side, it's clockwise to tighten, counter-clockwise to loosen.

On the pass. side, it's clockwise to loosen, counter-clockwise to tighten?

Has someone got a little rhyme to help us remember?


From Bill:

Passenger's (right) side has right hand threads - so clockwise (right) to tighten and counterclockwise to loosen.

Driver's (left) side has left hand threads - so counterclockwise (left) to tighten and clockwise to loosen.

Or, turn the bolt/nut to the front of the car to tighten and to the rear to loosen.

From John:

Here it is, right out of the 1962 Chrysler manual:

Page 29:

4. Loosen nuts (bolts) before using jack, particularly if you car has a Sure-Grip differential. Turn LEFT on the right wheels (passenger side of car) and RIGHT on the left wheels.

Question from Clay:

If memory serves me correct wasn't the left-handed threads on the wheel lug nuts only done on the drivers side? I would guess in theory it was a good idea, though I don't remember hearing about the brand X and Y autos having problems with tires and wheels leaving the vehicle. Does anyone know the years Chrysler had the left handed threads on their lugs?. Thanks to new tires and flawlessly performing Budd brakes, I have never had the hubcaps off my '67. Maybe it has them?


From Phil:

I am fairly sure that '68 was the last year for left hand lug nuts. And while we can say no one remembers wheels falling off the competition's cars, was that always true back in 1924 when Chrysler Corp started? I expect it was a very good idea at the time, on those old tall and skinny wheels they used, and like most traditions, carried on a lot longer than was necessary. Chrysler was always known for it's engineering, and it's the extra effort on little things like this, that has made me appreciate Mopars and especially, Imperials, more than most cars.

From John:

My '69 has both left & right lug nuts. The kid at Sears tells me I have a stripped lug nut. It was plain to see that he was trying to remove it the wrong way. And they wondered why I wouldn't let them put the hubcaps back on the car.

From Dave:

My first Mopar was a 69 Dodge Polara which had the left handed threads on the driver's side lugs. I'm not sure if I've ever been as angry and frustrated working on a car in my life as the first time I got a flat on the highway in the middle of a Mississippi thunderstorm and couldn't get the damn wheel off the car... like I said it was my first Mopar. I did figure it out after about 10 minutes of tightening the lugs. Thank God I didn't break any of them...

From Bill:

1970 was the last year for the left-hand threads on the left side of the car. Also the last year you could not lock the front doors by pushing the lock button down and close the door.

The first year was 1940, and the theory behind it was that centrifugal force of the moving wheel would keep the lug bolts (at the time) snug. It was felt that right-hand threads on the left side would result in loose bolts.

From Dick:

I see others have responded regarding the last year for this feature - I know my 69 LeBaron had the left handed threads on the driver's side, as did my 69 Newport. With a car with left handed lug nuts, I always put a bright colored (fluorescent yellow) note right on the wheel, warning the idiot with the air wrench, that it is left handed thread, and I also write it on the work order of any shop that I am having work on the car, and make the manager initial that he has read it. I had two rotors ruined by warping from excessive torque on my 69 by a stupid mechanic, fortunately that was back when you could still replace them.

Regarding the reasons for left handed threads: my own anecdote is that when I was a teenager, I was driving downhill in my 1931 F*rd Sport Coupe, when I noticed a wheel passing me on the left side. It took quite a few seconds of my musing that it sure looked like a Model A wheel, and what a coincidence that was, before I realize that I was missing my left rear wheel! Perhaps because I was going down a fairly steep hill, I hadn't felt a thing, and the car stayed up on 3 wheels until I came to a complete stop. I retrieved the wheel from a ditch, put it back on using one lug nut from each of the other 3 wheels, and made it home that way.

Question from Dieter (1955):

Just the other day I had to pull one of the wheels off my '55 Newport.  I had no problems loosening the lug nuts, they were very tight!  What threw me a curve was that the front wheel {drivers side } was fastened with left threaded lug nuts. I had another surprise coming - the rear wheels, also left threaded, are mounted with BOLTS going INTO the drum instead of studs sticking permanently OUT of the drum like on the front wheels.  Remounting the rear wheels is therefore so difficult to do, one has not only to lift the wheel {50 LBS}, hold it in place and then trying to find and thread the bolt into the brake drum. I don't see the logic in that design ,,, it's a bear.  Does anybody has any idea WHY Chrysler choose to this? Or do I have after market drums in the rear, they are shaped very much like the front ones though.  Any comments -- explanations on this subject are greatly appreciated.


From George:

Yes I can add some light. It is correct to have 'Left hand' thread on the driver side, all Mopars of that era had left thread on that side. One reason for the lug bolts instead of lug studs on the rear, is that you have about two inches less of obstruction to changing a rear tire, (although that not so important on your car with the full wheel opening) if you had studs it would be a tighter fit. But, I believe that for what ever reason it was more cost effective to manufacture that way, also it is said that lug bolts are stronger than lug studs, don't know for sure how true that is, but a lot of heavy equipment, trailers, especially horse trailers used this method. You should have a small locating pin between two of your rear studs this pin fits into the small holes between the rim lug holes. If it is gone, it may have been removed at some point so that a more modern rim could be fitted, also the center hole of the rim should fit snugly on the axel center flange to hold the weight of the tire when mounting.

Follow-up from Roger:

Good explanation, but I still don't understand completely why. It wasn't a matter of the price line of the car; '55-'56 Dodges came with lug nuts, Plymouths, DeSotos and apparently Chryslers and Imperials with lug bolts.

From Kerry:

My 54 has the same with bolts in the rear. Mine has a stud that you can 'hang' the wheel on while you fight getting the first bolt on.

Chrysler seemed to think that the rotation of the wheel would loosen normal threads on the left side so they used right hand threads. Don't know when the stopped. I think all mine had them. The 73 does.

Follow-up from Bill:

Chrysler first started using left hand threads in 1940.  The last year for them was on the 1970 models.

From Pete:

I can't tell you WHY this design is used but I do know that Mercedes Benz and some other German manufacturers STILL use it today. To make wheel changing easier, MB includes a handy little tool along with the jack and lug wrench. It's a long threaded rod that you install in the brake rotor after removing one of the lug bolts. Then, when you remove the other 4 bolts the wheel doesn't fall right off -- you slide it off the rod. Same for installing a wheel. You eyeball the rod location and then position the wheel to line up with it during installation. You may want to buy a 4" long bolt that fits the drum threads and saw the head off to make a similar tool.

Question from Loyal (1966):

I was wondering if there were any late model Chrysler (or other brands) that would have the same bolt pattern as my '66 Crown Coupe. They would also need to be the same size as the ones on my '66 because the tires are only a year old & I would just like to transfer them. I was going to purchase after market rims for it & I got to wondering if I could get a set of rims off an LHS, or Concord or something at the local U-Wrench-It.


From Mark:

Even if you found a proper bolt pattern, the offset of a FWD wheel on a RWD car would not work. The FWD wheels are offset inwards, the RWD wheels are offset outwards.

From William:

I believe that if you convert the metric measurements of the LH car wheels, this will be the same bolt pattern as earlier regular Chrysler cars with the 5 bolt pattern, but with metric lug nuts and appropriate tapers in the lug nut holes. The other main difference in using many late model wheels is that most late model vehicles are designed with bolt-on hub assemblies instead of them being cast into the brake rotor. This changes the backspacing of the wheel to compensate for that and makes wheels "fwd" or "rwd" in designation. The bolt-on hub wheels will have the center mounting surface closer to the outside of the wheel rim than the earlier styles.

Measuring what you have (from the mounting surface to the edge, but not the lip, of the inside of the wheel rim) before you go can be a big help. Also, taking a business card and marking the dimension from the center of one wheel stud to the center of the adjacent wheel stud and marking that on the card (which can also be used to note the backspacing dimension) is a good to do also. Be sure to also measure the center hole in the existing wheel. It can be larger, but not smaller.

The wheel you have might be a 5.5" wide rim, usually stamped on the inside of the rim (visible when the tire is unmounted) as "15 x 5.5 JK" or similar (for a 15" rim diameter wheel), so going to a 6.0" wide rim should be no big deal and not affect your existing tires. Most tires are designed to accomodate a range of rim widths, like from 5.5" - 7.0" with no problems (check some of the tire spec sheets at, for more specific information). Ideally, a tire's rim width would be within one inch of the tire's tread width (as mentioned in a magazine article years ago). Using a wider rim width will make the sidewall a little more vertical instead of in an arc, making steering response a little quicker but ride a little firmer as some of the "spring" of the sidewall to absorb road shocks will be diminished a little, for a given tire pressure.

Seems like there were some Lincolns and maybe Buicks that used the same bolt pattern as the earlier Imperials. Hopefully, a salvage yard with a Hollander Interchange Manual could also supply that information with respect to vehicles and particular year models. Of course, examine anything you purchase for damage and hopefully they will have some way to spin them to see if they wobble before you purchase them. Once you make a purchase, the yard usually will only swap bad items for other items in their inventory (or that they can get from other yards) rather than refund money.

From Rodger:

If you are short on early 60's wheels go find yourself a set of Ford 250 wheels. Other than that, that's it. Up to your year the lug bolt size is 9/16". The Chryslers and lessor vehicles used 1/2". Also the center hole is larger than what Chrysler or lessor cars used.

At one time you could purchase aluminum wheels under the Ford truck name.

From George:

I am sure you will find that they are the same patten as others like- Jeep, Suksie 4x4, Larda 4x4, none will fit correctly, but the patten is the same.

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