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Tires: late 1970's, not P-metrics... What to do for a Senior level car?

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We're about 98% done with a 5-year body-off nut & bolt restoration on the 1978 Mercury Marquis that my mom and dad bought new in August of 1978. Dad died when I was 14, I've been driving it since I was 16. Needless to say, it's been a sentimental journey!

As you might guess, the '78 Marquis isn't well supported by aftermarket suppliers! However, persistence and patience, a few parts cars, eBay, PayPal, and an extraordinarily understanding spouse have let us approach perfection.

We have NOS exhaust hangers, proper Duraspark ignition wires, Motorcraft belts, and a chrome bill that exceeds the car's original MSRP. I'm pretty excited with the results and also proud to represent the dinosaur era of big American sedans that have faded away.

But it came with JR78-15 steel belted radial tires. If it was a 1979, it would have been equipped with P225/75/15's and I could order those from a half dozen places. If it was an older bias-ply car, I'd be able to source proper tires in 3-5 days with standard shipping.

Factory sources give a clear paper trail that 235R15's (the Eurometric) were only available on '78 Marquis police cars. Hmm. My car is not a police car so the factory documents prove these tires would be incorrect.

The countdown to Auburn has begun! I realize I can probably earn a Junior with the wrong tires, but I'd really like the car to be properly out-fitted before it rolls onto any AACA show field.

Any ideas where I can source proper tires, or what tires and what documents would meet the Judging Guidelines?

Thank you!


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Don't know about your tire question, but just wanted to compliment you on a beautiful job. My father also bought a '78 Marquis brand new, and I inherited it when he died. It was the most comfortable car we've ever owned, and would accommodate most anything in the trunk -- incredibly useful for a family of four on extended road trips. I wish I'd kept it.

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I think it's just a case that the industry's

DESIGNATION of tire sizes changed.

The tires themselves are virtually identical.


I don't claim to be a judging expert, but

I believe you should be fine.


Nice car, by the way.  I appreciate cars of that era--

so comfortable and so good on the highway.

You're almost a pioneer in restoring a late 1970's car,

but in a couple of decades, there will be plenty

more people like you.

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Thanks for all the kind words! The car has come a long way from dry-rotted body mounts and caked on Ziebart.

I'm not sure if I'm a pioneer or a lunatic... it's astounding how many more parts are on the '78 than my '66 Cyclone GT. Restoring cars from the 70's might be slow to catch on, especially if an HPOF car can simply be preserved instead.

But this car is restored and I'd like to see go through Class Judging and I want to be as well-prepared as possible.

I just spoke with Chis at Universal (Mike wasn't available) and he was terrific... but he said the JR78's all disappeared years ago. They have a nice P225/75R15 that would be very sympathetic, but a recent issue of Antique Automobile said the P-Metric tires "came about in 1979 and is therefore not of the era".

I agree the "P" is mostly a designation and the actual difference in tire design and capabilities is nearly indecipherable, unlike the differences between a bias ply and a steel belted radial... but the article says what it says so I'm still not sure what tires would suitably complete this restoration odyssey... or where to find them.



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From the Judging Guidelines:


"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."


Do the required research and send a letter to the VP of Judging. The VP of Judging's address is:


Herb Oakes

102 Converse Drive

Jacksonville, NC 28546

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Thank you Mr. Hinson. 


I believe I've sent everything required to Mr. Oakes and I check my mailbox everyday, but so far no letter.  I can't imagine how busy he is as we approach car show season, or how many requests he might receive.  I'm hoping to find an alternate path forward should, for whatever reason, I not qualify for an exception letter.


Currently my only viable path, aside from receiving the ONLY AACA ACCEPTED (at least they are clear on that!) documentation would be to locate a set of 38 year old tires for my freshly restored car.  Driving on tires that old, even at just 20-30 mph, terrifies me.


Interestingly (at least when you gnaw on this issue long enough), it seems almost impossible for the tire manufactures to comply with AACA regulations for the cars originally equipped with HR/JR/LR tires.  Federal Motor Vehicle Safety Standard #139 (a rule from around 2000-2002 depending on which variation you look at) regulates all tires fitted to cars manufactured after 1975 and stipulates all sorts of information be on the sidewalls... the very same information that would be "not of the era". 


'Tis a conundrum!

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There's no conundrum here--Matt Hinson provided you the answer.  I'm having the same discussion with a member in our region who recently purchased a 1978 Cadillac Eldorado, which also came with non-P-metric radials (LR78-15) and can't find original-size reproductions.  You followed the correct process by mailing a letter to Herb Oakes with the necessary documentation (info from at least two manufacturers stating the original size tires are not produced nor a size up or down, and proposing the equivalent size in P-metric). 

Herb is probably at the AACA Meet in Naples this week.  My recommendation is that you e-mail him and politely ask for a status check on your request.  It's possible your original letter did not make it to him or, depending on when you mailed it, he may be researching the issue.

Even if you were able to find the correct size original NOS tires, you're right--it would not be safe to drive them, nor does AACA expect you to do this.

Check with Herb.  There's a reasonable solution to this that will allow you to comply with the AACA's judging guidelines.  Once you have your letter from Herb, mount the approved tires and make sure you show your letter to the Judging Team Captain before they begin judging your car.  (Team Captains usually walk the field ahead of time to ensure all their assigned vehicles are there, to look at them quickly, and speak with the owner if they have any questions.  This would be the best time to tell them about your car's tires and show him/her your letter.)

My wife and I are going to be at the Auburn Meet.  I look forward to seeing your Mercury Marquis.  It sounds like you've put a lot of work (and expense) into it, and I bet it looks great.

Edited by Mark McAlpine
Corrected Matt Hinson's name (see edit history)
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'78 was an interesting year. My Sunbird came with BR70x13 Firestone 500s which met Bill Neely's comment of "not even safe in the driveway'. Know I lost the tread on a couple.

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Beautiful restoration—you have my sympathy on the tires. For years, the only new 1984-1986 Chevrolet Corvette tires available in the correct size were drag radials. Recently, BF Goodrich through us a bone, but who knows for how long ...

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