The Bizarre Michelin TRX Was The Betamax of Tires, But Sadly I’m Stuck With It

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One of the things people notice when I’m out and about at various car meets in my Ferrari is not just the goth rock star driving it. Once we get past the inevitable tedious questions about what band I’m in, and no seriously you must be in a band looking like that (unlike my Autopian wingman S W Gossin I can’t play a fucking thing. He got the musical talent and the voice, I got the style) the next thing people comment on is its originality. I’m only the second owner, and it still has the HR Owen license plates, dealer stickers and tax disc holder it had when it rolled out of a fancy pants Mayfair showroom in London forty years ago. That extends right down to its wheels, people saying something along the lines of “you don’t see many of these on their genuine alloys anymore”.

Yes those fucking wheels. I hate them. They’re too small and the offset is terrible – they’re the one thing I’m desperate to change. But I can’t. I’m stuck with them for now. Why? Because my Mondial rides on the Betamax of tire technology, the Michelin TRX.

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What is Betamax? Dear summer children. A long time ago old men like your Uncle Adrian and Uncle Jason survived something called the format wars. In the late seventies the technology to record your favorite programs from the telly box onto magnetic tape for viewing later was becoming a reality. It seemed like witchcraft, and ten year old me genuinely thought you could use the fast forward feature to skip through to programs that were on next week. To cut a long story short, there were two emergent formats; Betamax invented by Sony, and VHS introduced by JVC. Betamax was more expensive and boasted the superior technology with a glorious 250 lines of smear-o-vision, but Sony wanted to keep Betamax proprietary and license it out. JVC decided the best way to encourage the adoption of VHS was to make it an open standard, allowing competitors to make VHS machines. This drove down the cost, VHS was adopted as the default standard, and by the mid-eighties Betamax for the home consumer was deader than Jason’s RV (although it found a second life in professional broadcasting).

Now we’re all caught up on obsolete home recording technology, what the titting hell does any of this have to do with the round rubber things we put on our cars. We’ll get to that. First of all, let’s have a look at one of the tires on my Mondial.

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You can see the size is 240/55 VR 390. In the name of all buggeration what kind of size is that? For those of you that skipped car design class when we talked about wheels here’s a quick primer on how to read conventional tire sizes from our friends at Ford UK:

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In the above image, the 175 is the tire width in millimeters. 65 is the profile of the tire expressed as a percentage of the width: in this case the sidewall depth is 65% of 175mm or about 114mm. R14 refers to the diameter of the rim in inches. Finally the load index 82 means a maximum load for that tire of 475kg, and T is the speed rating, indicating this tire is safe from exploding up to speed of 118mph. This nomenclature is universal across all modern radial ply tires. Yep, a confusing mix of metric and imperial. Did us British come up with this?

So let’s decipher the size of the Mondial tires together: 240mm wide, 55 profile, speed rating of V (up to 150mph) and 390. What the fuck even is that? If you guessed it’s the rim diameter in millimeters, well check out the brain on you. Goddamn French and their science based system for weights and measures. Why can’t they use imperial freedom units for the rims? Turns out this was a very deliberate decision surprisingly not based on typical French stubbornness and arrogance but one of safety (in case you think I don’t like France, not true. In common with most bougie Brits I love France).

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When they weren’t drawing maps or dining out in snooty restaurants why did the bods at Michelin decide to introduce a whole new type of tire? Turns out Michelin have a bit of form for tire innovation. Traditional bias-ply (or cross ply) tires were made by laying the internal cords at an angle from the inner to the outer bead at an angle of thirty to forty degrees. Each layer of cords (plies) would be placed at opposing angles, hence the name cross plies. This gave superior ride comfort but shitty grip and the cords rubbing against each other under load would produce excessive amounts of heat, leading to blow outs.

For the French, no doubt concerned with such pressing matters as getting to the restaurant on time or rushing to meet the mistress, an impromptu wheel change at the roadside wasn’t ideal. So Michelin developed the radial ply. Placing the internal cords at ninety degrees across the carcass of the tire, this resulted in a much stiffer tire that gave better grip and was less prone to exploding when you were late for your dinner reservation. At the time, Michelin owned Citroen, so one of the first cars with radial tires as standard was the 2CV of 1948, although you weren’t exactly getting anywhere quickly in one of those.

Nonetheless, the loping ride and long travel suspension of the 2CV masked one of radial’s initial drawbacks over a cross ply; a ride that would turn your spine to cookie crumbs. At first this wasn’t a problem; another total waterbed on the ride comfort front, the 1970 Lincoln Continental MkIII was the first American car to roll out of the showroom on radials. But by the end of the sixties cars were getting faster, heavier and thanks to increased highway construction, traveling at higher speeds for longer. These factors along with a new generation of supercars, demanded lower profile radial tires be developed. Michelin wanted to develop a tire that would combine the benefits of a low profile with a good ride quality the French were famous for.

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Image: Michelin Classic

Michelin’s solution was to design a complete wheel and tire as a system. In 1975 they introduced the TRX. This used a shallower flange where the bead met the rim, allowing for a more even distribution of stress through the sidewall, giving it its name. TR for “tension répartie” (distributed stress) and X after the original Michelin radial X. According to Michelin:

“For the first time, the tyre and its rim complemented one another perfectly, working together as a single unit. The rim therefore underwent a fundamental transformation, the essential characteristic of which was a flatter, lower flange. This new design of the rim and the bead of the tyre resulted in a gradual curvature of the casing without the “S” shaped flexing inherent in traditional designs.”

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Because fitting a TRX tire on a non-TRX wheel would be extremely dangerous (due to the different bead seating), Michelin wisely decided to size the TRX in millimeters as opposed to inches, so they physically wouldn’t fit a normal road wheel. TRX sizes ran from 315mm (12.4”) fitted to hotter versions of the Austin Metro all the way up to 415mm (16.3”) on early models of the Ferrari Testarossa. The first car to have them as standard fitment isn’t entirely clear, but by the early eighties the majority of French luxo-barges including the Citroen CX, Peugeot 504 and Renault 30 came with them, along with the most Ferraris, 2.8 injection models of the Euro Ford Granada and some BMWs. On account of their cost, they generally only appeared on higher end models.

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Back then Ford of America was constantly giving its Euro division the glad eye. When they rolled out the Fox platform the idea was to have a more Euro influenced lineup of cars. As such, the ‘Built With American Ingenuity’ 1979 Mustang could be optioned with French TRX tires. Astonishingly, the 1980 Thunderbird came with whitewall TRXs, which I imagine involved a Lethal Weapon 2 style container full of dollar bills being shipped from Detroit to Clermont-Ferrand.

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And this is where my taking up half the article with Betamax nonsense becomes relevant. Despite being technically the more advanced system, when Sony introduced Betamax, it would cost over $2000 to put one underneath your television. In 1975. That’s a staggering $11,000 today. And the first tapes could only record for an hour. VHS, introduced to the American market two years later, could record up to three hours and was much cheaper. Fellow ballpoint fondler The Bishop found out ticking the TRX option box when ordering your 1979 Mustang would cost you a princely $298 ($1252 in 2023) on top of the $4828 for the hatchback (because who the fuck wants a notchback Fox body Mustang?). Or over 6% of the base price. Because they needed bespoke rims, if you wanted fancy French tires, you were paying fancy French prices.

It wasn’t just the expense that did for the TRX. Due to the special way the bead sealed against the rim, if you got a puncture, you had to find a tire shop that had the necessary equipment to change them. Not only that, you had to have a Michelin replacement – there were no budget ditch finder specials you could swap on in those days. A couple of other tire manufacturers did dabble in the TRX system, notably Dunlop and Avon, but by the mid-eighties traditional low-profile radials had negated much of the TRXs advantage in ride quality. They appear to disappear from the Mustang options lists by 1985, and Autocar’s June 1986 road test of the Mondial 3.2 shows the tires as being TRX, possibly due to Ferrari using whatever was laying around in the factory to build cars. But there’s no doubt they reverted to imperial sizing by 1987.

1982 Michelin TRX Tire Print Ad, Radials Grand Prix Circuit New Concept Man | eBay

When I went and viewed my Ferrari in December 2021, it had just emerged from a period of hibernation after the original owner parked it in his barn when he replaced it. I took one look at the tires and knew they wouldn’t go through an MOT test, being well out of date and having a sidewall texture like rhino skin. A full recommission and fresh MOT test was part of the deal, so I paid a deposit and went home to search for a set of imperial alloys from a later model, which I found on eBay for £650. A day or two later the dealer called me to say he’d put four brand new TRXs on the car at a cost to him of £1600.

If he’d called me to ask what to do I’d have told him to knock the cost off the asking price of the car and I’d have bought the imperial wheels I was watching. Now I’m stuck with the sodding TRX wheels because the tires are only 18 months old, and with the mileage I do in the car, they’re unlikely to wear out anytime soon. But we must give full credit to Michelin for continuing to support the TRX, even if they are still bloody expensive.

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129 thoughts on “The Bizarre Michelin TRX Was The Betamax of Tires, But Sadly I’m Stuck With It”

  2. I remember the Fox Mustang launch and the TRX tires since Road & Track did a feature article and I blagged brochures at the NY Auto Show.
    The Betamax analogy does catch the equipment and cost issue but missed the killer app for VHS, porn. Sony wouldn’t supply the smut makers so they went VHS. They wised up during the later Blu-ray versus HD DVD conflict and let porn studios produce Blu-ray ensuring the triumph of that format.
    As an aside the physical Betamax tape was also used for the Betacam professional format in early camcorders. These ran the tape at higher speed and used component video to get better quality than the 3/4″ U-Matic on smaller 1/2″ tape.

  3. This is flashback overload for me. First, the TRX flashback. My neighbor had those tires on his Mercury XR-7, I think it was a 84, and he got super turbo pissed at the cost to replace them. He parked the car and drove his POS work van until he could figure out how to get tires cheaper. I don’t know how he did it, but he eventually got the tires.
    Second, is the VHS players. In 1982 a store had the VHS players on sale. They were $10.00 off a price of $999.99. This is in crappy economy 1982. I also remember a copy of the movie MASH was $299.99 at sears.
    Ahh, the good old days.

    1. When I was in school a friend of mine bought a copy of The Living Daylights (best Bond film, fight me) on VHS. It was something like £79.99. And this would have been about 1988.

      1. He could have just recorded it off the telly at christmas, that’s what we did 🙂
        And Living Daylights is good, but it’s still no On Her Majesties Secret Service…

        1. IIRC The Living Daylights didn’t get its TV premiere until the early nineties. I remember it being trailed by LWT (there’s one for the teenagers to look up!).

    2. They used to price those prerecorded movie tapes really high at first for selling to video rental stores and then the price would come down after a couple months to like $19.99. Which was still expensive.

  4. Never drove a Mondial, but do have some time in two TRX-equipped cars: A ‘Stang and a Renault 5 Turbo. All I can recollect about the tires is that they were approximately round, and separated rims from asphalt. If they had any advantage, it was lost on me.

    Supposedly Mustangs so equipped also had a “TRX Suspension” package. Again, I recollect nothing about that. I do know that other Fox-platform Mustangs handled well enough to suit me, so the option wasn’t an option.

    I knew several R5 Turbo owners who wisely stashed the TRX wheels in their garages and replaced them with inch-sized Gottis. The things were still expensive little rocket sleds, but at least replacement tires were a) pretty readily available and b) a good bit less cheaper.

    1. A couple of people have said to me at shows that by modern standards, TRXs are pretty hard riding. The Mondial isn’t too bad, but a sharp transverse ridge in the road surface sends an almighty crash up through the steering column.

  5. Gosh, I thought the endpoint of this story was that you can’t get TRX tires anymore and you can’t find rims to fit the car. What exactly is the complaint? And ironically I was just sorting through some stuff in the basement and I found an old home video…on Betamax.

    1. The complaint is that, while you can still get TRX tires (made by Coker for Michelin), you’re paying 2023 performance tire money for 1975 technology tires.

      2. They are not 1975 technology, they are every bit as advanced as modern tires, as they did benefit from Michelin’s research ever since.

        What the point is of putting them on 50 years old rims is another story.

  6. Good article. You have the car, the wheels, and the tires. You are not wearing them out anytime soon. They look great on the car and handle just fine. I understand that a Happy Goth is an oxymoron so just frown and go with it. Really, I owned a BetaMax. It’s all good.

    1. Researching this article was nearly fatal on a couple of levels. Not only did I start lusting after a ‘79 Cobra in black with the green decals, I suddenly realised I was looking for a mint in box Sony Betamax recorder, even though it would essentially be a big Japanese paperweight.

  7. Ran a tire store back in the 80’s…It was cheaper for the customer to buy regular tires and WHEELS than it was to buy a set of TRX tires at the time. Any time a Ford pulled in I had my comparison chart ready. Recommended the customer keep the TRX wheels…they didn’t want them. Gee I wonder….NOT.

    1. I worked at an auto parts store that sold tires in the early Eighties. It seems the Ford sales personnel failed to tell the buyers how much it cost to replace those tires. I was subjected to the anger and unwarranted personal abuse from a lot of people when I told them four of them ran close to $1k (1980 dollars, remember) and they would need to find a place that would mount them. It was a time of “the customer is always right” so I just had to stand there and take their shit. If I could time travel back, I would have told them to go fuck themselves.

  9. I think I’d go to the inch size wheels and cheaper tires and keep the TRX wheels and tires in the cool of the wine cellar where they won’t deteriorate.

    1. That is the plan, but I can’t really justify the expense at the moment. I am keeping an eye out for another set of wheels on the dreaded eBay.

      The wine cellar is full of wine, so I’ll stick them in the servants quarters which are not heated.

      2. I got mine from a [spoiler title=”not advertising”] Mr Fiat [/spoiler] (probably not his real name). Not cheap by any stretch of the imagination, but even with a set of Coopers they were still cheaper than the prices I was seeing for replacement TRXs (to say nothing of the turnaround timeframe and ease of installation).

  10. Mustang trivia – as a cool little easter egg, the SN95 Mustang base model came with wheels that basically (5 instead of 4 lug bolts IIRC) replicated the Fox body TRX wheel design!

  11. While there may have been whitewall TRX tires, that’s not what’s on the Thunderbird in the photo. Those are 14″ steel wheels with wire wheel covers. The TRXs that were optional on Tbirds used a much sportier looking wheel.

      1. At the same time,I got some OG apple logo stickers that came with our Apple ][+ and 2 unopened boxes of those luxurious double sided 5-1/4 disks. Maybe if he asks nicely…

  13. Very interesting article, Adrian. But now we need a follow-up (seriously): how were non-TRX radials improved to avoid the rough ride of the early radial tires? What other innovations were tried and how are modern radials different from the early ones?

    Also, this caught my eye: “Fellow ballpoint fondler The Bishop “. Ballpoints? How modern of you! I do have some 1960’s and 70’s era Parker ballpoints, but my daily writers are all 1940’s – 1960’s Parker fountain pens. Now that’s the right way to write! All four of mine are variations on the famous Parker “51”, the epitome of functional fountain pen design, IMHO.

    1. I mentioned it in an older article, but most designers eventually circle back to the classic Bic crystal for sketching thumbnails on paper.

        1. FWIW my daily driver is a Lamy Safari fountain pen. Black ink, although I’m considering a switch to purple (which is apparently what Enzo used).

          1. The Safari is a solid choice for a fountain pen, IMHO. My Parkers are blue, burgundy, green and grey. I use Noodler’s “Bad Blue Heron”, “Red-Black”, “Bad Green Gator” and “American Eel”, in them, respectively.

      2. Too smudgy.

        Entire design department here switched to Pilot Better Retractables. Cheap AF, no smudgy, better details. Try one out. I love them.

        1. You know what blew me away just three days ago? Cheap-ass Paper Mate ballpoints at the mechanics. So surprisingly smooth and glidey.

  14. Great history reminder. Although the availability of VHS compared to Beta, especially for pre-recorded tapes was also a big driver for VHs’s success.

    That said, I’m amused when the owner of a decades old Ferrari whines about costs…..

    1. VHS had longer record times which made a huge difference. They were used for recording TV shows long before Home Video was the thing. BetaMax was already losing when home video came out, therefore not as many movies were released on it.

      1. This is such a huge thing. VHS made the intelligent trade off to allow longer time per tape, at the minor cost of a little size and a little picture quality. This meant VHS WAS BETTER THAN BETA.

  15. “This nomenclature is universal across all modern radial ply tires.”

    Ah, there’s your problem. I recently put a set of 7.50-16LT tires on my ’70 International 1200D:

    https://www.stausaonline.com/tires/sta-super-traxion/

    for the low price of… Come to think of it, those weren’t particularly cheap, either, which I suppose is to be expected from a company whose name starts with “Specialty.” As with TRX tires, I’m just glad someone is still making them.

    1. They make them, but they’re generally in limited runs with years in between, so for long stretches they’re unavailable. Then when Coker DOES make some, people snap them up since it could be another decade before another batch comes to market.

      1. Coker lists STA tube-type tires on their site but not tubeless, so I had a local tire shop order the tubeless version directly from Specialty Tires of America.

  16. Loving the Mondial content–and Adrian’s tone of excited regret! I immediately got 16″ replica rims and reasonably priced tires for my ’83; had to shave down the bolts a bit on the rears, but nobody besides other Mondial owners will notice mine aren’t OEM.

  17. I bought new a 1979 Mercury Capri (for those outside the US, a Mustang with a different grille) that had the TRX radials and the Recaro seats. The Recaros were lovely, replacing the TRXs less so.

    1. I had a set on my 1983 Mustang GT. When Ford upped the TRX size from 190 to 220mm for 1983 on the Foxstangs, they also changed to a different tread pattern, which was really hard to get. I drove over some debris that took out the sidewall on one of mine and I had to replace two tires because nobody wanted to sell me one tire with a tread pattern that didn’t match the other three. Ouch!

      At that point, I started looking for replacement wheels. The Mustang SVO never came with TRXs, it came with Eagle NCTs – I figured that I would look for a set of takeoff SVO wheels but it turned out that the bolt pattern was also different on the SVO.

      A couple of years later Ford finally dumped the TRX and went to Eagle GTs like everyone else in the industry.

      1. Yes you had to get some kind of updated suspension as well. I spent far too long looking at old Mustang brochures on the Ford Heritage Vault and now want a ‘79 Cobra in black with the green decal package.

  19. Finally, someone else who doesn’t get the notchback obsession on Fox Mustangs.. I had a ‘91 hatch in Calypso with a grey interior.. it didn’t get much more ‘90s style than that and it was glorious!

    1. The notches are a little lighter and a little stiffer due to the smaller hole for the trunk vs hatch. So they were sought by drag racers.

      Looks-wise, no contest, the hatch comes in a solid second behind the convertible.

    2. One reason was the California Pursuit cars were notchbacks. The other big one was that Tony DeFeo used a notchback LX writing in Cars Illustrated about how to blow people’s doors off cheaply.

      *internet source/YMMV/grain of salt & all that

  21. Let’s all remember one of the biggest reasons that Beta lost…

    I read the article, have worked selling tires in the distant past…never heard of this size/brand/model. I will just look at the pics of the classic Ferrari instead.

    2. Beta had already lost when porn on tape became a thing, that’s why there was no porn on it: they weren’t going to make tapes for the loosing standard

  22. No you’re not! There’s superformance.co.uk 🙂

    Also, with teh Mustang, most people chucked that TRX shit and replaced them with regular rims.

    Michelin would try this shit again 20 years later with PAX, on cars like the Honda Odyssey. Again, most people just replaced them with regular wheels.

    1. Neighbor had an Oddy with the oddy wheel-tires. None of the major/national tire shops would do the switch for liability reasons. Not being a mechanically inclined person, he eventually took the van to some tire shop that only has signage in Spanish and they had them swapped out in 20 minutes flat.

    2. I don’t want to pay their prices, and I want to make sure I get the later spoke pattern, which going by their images I’m not sure their version is.

      1. They seem to look like what you have on the car now, and they’re probably going for period-correctness.

        Any junkyards or something? With all the jokes about Ferraris being unreliable and going to the junkyard, maybe used wheels from a QV or 3.2 may be available.

        also obligatory: Ferrari isn’t the car for people who “don’t want to pay their prices” (sorry, I had to!) 😛

    3. I was about to mention the PAX runflats on the 3rd gen Odyssey. If you ever see a Limited trim Odyssey rolling on BMW wheels, getting rid of PAX was the reason why.

  23. My family was Beta-first when I was a kid. We had a Sanyo Betamax with a remote control that was connected to the unit via a 20 foot-long cord.
    I used to record a lot, and I still have the whole first season of The Simpsons on Beta, recorded off of WFLD and complete with original commercials.
    Sometime in the 2000’s, I bought a nice Beta on eBay (with a wireless remote). I also picked up a rewinder, since using an old VCR to rewind will kill it sooner. I haven’t hooked this stuff up in while, maybe because old videotape looks horrible on a modern flat-screen TV. Of course, I do have that old Hitachi 20″ from 1985…

  24. When I was 18 I had a GM car and wanted some alloys, found a set on clearance and had the salesperson hold them for 2 weeks till I could save up some dough, went to pick them up and the clerk essentially told me that I would not want these as they were TRX and tires were expensive even in 1984, I thanked him and walked away

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