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JR78-15 for 1978 Mercury Marquis?


gpfarrell
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After 4 1/2 years of restoration, my first car... the '78 Marquis my dad bought new... is nearly done.

I have a tire dilemma.

It was originally equipped with JR78-15 white walls. The mid-70's radials don't seem to be supported by the aftermarket though, and I'm unable to find either HR78s, JR78s or LR78s anywhere.

Are P225/75-15s accepted? I know they're "wrong" but I'm not sure where to turn.

Even the mighty Coker website says they have no tires for my car. :(

Any ideas? Any other sources

Thank you!

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Edited by gpfarrell (see edit history)
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Nice looking Marquis!  I know you'll enjoy getting it back on the road and driving it again.  Try Lucas Classic Tires.  Looks like they have G, H, and L 78's available.  Here: http://www.lucasclassictires.com/Search-by-Tire-Size_c67.htm

 

If your unable to find the correct original ones like the HR JR LR ones then the modern radial replacement ones would be accepted.

 

Hope this helps,

Matt

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With the great tire shortage of 1976 and the new car purchasers of that year not receiving their spare tires until late 77, odds are pretty good that your dads car was delivered wearing a set of Michelin P225's.

 

I'm 98% sure it had B.F. Goodrich's...  I think LifeSavers?  I have an HR78 that was the OEM spare from a parts car.  I think the 225's hit the showroom in 1979, but I'm getting conflicting signals so any information is much appreciated! 

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Nice looking Marquis!  I know you'll enjoy getting it back on the road and driving it again.  Try Lucas Classic Tires.  Looks like they have G, H, and L 78's available.  Here: http://www.lucasclassictires.com/Search-by-Tire-Size_c67.htm

 

If your unable to find the correct original ones like the HR JR LR ones then the modern radial replacement ones would be accepted.

 

Hope this helps,

Matt

 

Thanks Matt... those tires Lucas shows aren't radials so I think I'd be more "wrong" with bias-plies.

 

Does anyone know what I need to show the judges to avoid a penalty for sporting P225/75-15s?

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A letter from the VP of Judging.  See the following from the Guidelines, including "c.":

 

12. The following identifies the first year of

tire sizing for the various designations.

Tire Documentation

Owners not able to find a correct

replacement tire should send a letter to

the VP Judging indicating the specific

size of the correct tire and that at

least two tire manufacturers have

been contacted and the correct tire is

not available. Tires one size larger or

smaller are acceptable. A letter from

the VP Judging is the ONLY AACA

ACCEPTED documentation regarding

a vehicles’ substitute tires. Any letter

issued by the VP Judging should be

shown to the Team Captain at the time

of vehicle judging.

IT IS IMPERATIVE THAT THE TEAM

CAPTAIN ASK FOR DOCUMENTATION

FOR ANY TIRE THAT IS QUESTIONED

BY THE CHASSIS JUDGE OR DOES

NOT MEET THE FIRST YEAR OF

MANUFACTURE GUIDELINES

LISTED BELOW. Some manufacturers

offered a radial tire - for specific

vehicle(s) - as a factory authorized

option to the standard issue ply

tire. The use of red line radials on a

vehicle should be accompanied with

documentation. It is advisable to seek

documentation from the vehicle owner

when a tire size or type is in question.

This is especially so in cases of limited

production, specialty vehicles, and

foreign made vehicles.

a. LETTER SIZE tires, i.e. G78-15,

GR78-14, etc 1967.

b. RADIALS, i.e. 185R14, 175R13,

etc. Domestic Cars. (Factory

documentation is required for any

vehicle with radial tires prior to the

years listed below.) Some domestic

manufacturers offered these tires

as early as 1967, such as Buick

and Oldsmobile. It is possible that

others may have offered them

as well. BEFORE taking any

deductions, the Team Captain will

ask the owner for documentation.

(Note: European built vehicles

can be much earlier) (Japanese

vehicles 1967, possibly earlier).

c. LOW PROFILE METRIC RADIALS,

i.e. P195/70R13, P195/70VR14

Domestic Cars as early as 1976.

European cars 1969*, Japanese

cars 1975*

* Also refer to above Note when

judging foreign made vehicles.

Edited by Phillip Cole (see edit history)
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I'm 98% sure it had B.F. Goodrich's...  I think LifeSavers?  I have an HR78 that was the OEM spare from a parts car.  I think the 225's hit the showroom in 1979, but I'm getting conflicting signals so any information is much appreciated! 

Rubber bounced with the communist take over of Viet Nam and it didn't stop bouncing until the great gas crunch of 79 temporarily curtailed the demand for big cars with big tires. French Michelin had access to Viet Nam rubber when US companies didn't and what got done, got done.

 

During the great tire shortage whatever could hit the showroom floor did and most of those cars came with an IOU for the spare. When the spare tires came, they came for what should have been on the car and didn't always match what came with the car. The alloy wheels and the badge on the roof pillar in your posted photo tell me that it's not the base model, it could even be a Grand Marquis and depending on when it was built, your car could have come with Michelin 225's, a steel wheel in the trunk and an IOU for the spare. Factories did what they could to keep the assembly line moving so even if it didn't come off the truck with Michelin's, a steel wheel and an IOU, Lincoln Mercury dealers that also sold Michelin put full sets on the big money cars and the lesser brand factory tires became spare's for their screaming customers. 

 

I haven't given the great tire shortage of 76&7 any thought for a long time, but what I remember, I remember well. Dad was running the biggest Lincoln Mercury store in the city, across the road his cousin George was in charge of the biggest Cadillac store, North and South in the smaller towns his other cousins owned their Ford and Chevy dealerships. The topic of tires was a part of any family get together, Dealers did charge backs, tire swaps and trades with each other, and the factory reps either said OK or they didn't want to know. 

 

If you did a frame off restore and you're looking to have the hundred point car, follow the rules. If you want something that's right for the time P225 will do and if you want to know for sure what came with the car new look inside the owners manual, you might get lucky and find the original tire warranty paperwork that came with the car.

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Interestingly, I just got my copy of "The Judge" for January.  Under Approved Changes for 2016 Judge's Guidelines it says: "Item 12, c. changed P-Metrics for Domestic cars to 1979, from 1976"  That rules out the P-Metric in 78, I guess.  You need to write Herb Oaks, VP Judging, and tell him what you have found.

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Thanks Digger for the cool history lesson! My car is a base Marquis. I much prefer the optional forged aluminum wheels I installed, but I'd likely mount the proper tires on its proper steel wheels and fit the hubcaps for the judged shows. I'll use less-proper but better driving tires on the aluminum wheels for driving.

In high school I has whitewall Pirelli P77's on it... They wouldn't last but they sure did stick!

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I can't follow your logic. Were any American tire manufacturers using natural rubber by 1979? I know Michelins were natural rubber but weren't all American tires synthetic? I can see how there was a rubber shortage and remember it well  but wasn't it because a lot of it was going toward the war effort rather than any shortage of natural rubber coming out of Viet Nam ?

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I can't follow your logic. Were any American tire manufacturers using natural rubber by 1979? I know Michelins were natural rubber but weren't all American tires synthetic? I can see how there was a rubber shortage and remember it well  but wasn't it because a lot of it was going toward the war effort rather than any shortage of natural rubber coming out of Viet Nam ?

South Viet Nam was loaded with rubber tree plantations and the war had to be fought around them. Our Viet Nam war effort ended when we started pulling troops out in 74, our direct link to Viet Nam rubber ended when the last chopper left the embassy roof in 75 and by 76 we were feeling the pinch.

 

Everything I know about making tires I learned from public television and to properly answer your question I Googled how to make a tire. Tires are still made with natural rubber, carbon black was the first additive for strength and synthetic rubber is blended into the natural rubber to change it's characteristics.

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P-metrics did start in about 1979 model year.  They replaced the prior alpha-numeric sizes, which replaced the prior size "size" designations.  JR78-15 replaced the prior 8.85x15 size.  HR78x15 replaced 8.55x145 similarly.  LR78x15 replaced 9.15x15.  In reality, as things worked out, the "J" designation didn't last long with the H and L designations filling in that space.

 

For the 1975 model year, GM came out with their GM-spec radials tires on almost all models.  The first all-season rated radial they'd ever used, with a unique-to-those-tires tread design.  Almost every brand of tire had a GM-Spec radial in their lineup, except possibly BFG.  Uniroyals usually went on GM cars, BFGs were on Mercurys and many other Ford cars.  The tread design was similar to the GM pattern, in orientation, but not exactly like it in all respects.  I termed them "Ford Spec" tires as that's the only place they went (or at least all that I saw them on OEM).  When the higher-pressure (35psi max rather than 32psi max) P-metrics came out, those "Ford Spec" BFG radials were history.

 

In reality, I believe that if you convert "225" to inches, you'll find that it's pretty much accurate, size wise, for the earlier 8.85 and JR78x15 tires.  That ensures they'll "look right" on the car.  In Tire Rack's website, there are still some P225x15 whitewall tires available, but probably from an Asian maker or Firestone as many seem to be abandoning that size in their listings.  Just as they abandoned the HR78x14/P225x14 size several years ago.

 

I KNOW you want the car to look correct and judge "GREAT", but I'd be more inclined to have a P225/75R-15 whitewall on it, which was of the correct dimensions, in a tire that could be obtained for less than the repro radials price, than anything else.  This also means that you'll have to ensure that any other points deducts which might happen DON'T, in sort of a compensatory manner.  In other words, that if the car doesn't place very high, it won't be just the tires' fault.  In this orientation, you might seek out the help of other members to judge the car before the meet, for good measure.  Or seek out other cars which placed high and see what they did.  Obtaining a blank judging sheet might help you see what's what, too.

 

NTX5467

Edited by NTX5467 (see edit history)
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  • 2 weeks later...
  • 4 weeks later...

If you are planning on AACA judging you need letters from two tire companies stating that a JR78-15 is not available.  Send copies of the letters to Herb Oaks, VP Judging along with documentation that your car originally was equiped with radials.  Also state the size tire you would like to use instead.  It looks like a 225R15 or P225/75R15 is the tire you should request to use.

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  • 2 weeks later...

I've sent my letter to Mr. Oakes so hopefully I get his blessings.

While I appreciate the vast differences between bias plies and radials, the nomenclature on radials seems to be trivial. It's odd to me that many underhood tune-up parts can be aftermarket auto parts store parts (like ignition wires and batteries for instance) yet the rules on tires are so specific. The rules work well for bias ply cars and post-1979 cars, but the mid-70's cars that are growing in popularity are caught in a tire vacuum, especially if the owner wishes to maintain the whitewalls that were a fixture in that era.

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  • 3 weeks later...

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