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

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).

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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?

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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.

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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.

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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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changedmynameasIworkinadealershipandsomeofourbrandsarentgreat
changedmynameasIworkinadealershipandsomeofourbrandsarentgreat
9 months ago

I’m guessing the weird rims and tyres on the Renault Fuego are TRXs

Geoff Buchholz
Geoff Buchholz
9 months ago

Between tires, home video and writing implements, this whole experience was a pedant’s delight. Thank you all. This is why I upgraded to Velour.

ToeMotor
ToeMotor
9 months ago

I had an 83 Capri, 5.0 Black Magic. I bought it in 87, and at 19 years old, I just wanted the 5.0, and the 4spd…..
I didnt think anything about the tires, until I needed to buy new tires……
Any ideas how hard it was to find metric tires…., let alone how expensive they were!!
But damn wasnt it a good looking car!!

https://k2rev.blogspot.com/2015/10/1983-mercury-capri-black-magic-edition.html

Guillaume Maurice
Guillaume Maurice
9 months ago

I imagine involved a Lethal Weapon 2 style container full of dollar bills being shipped from Detroit to Clermont-Ferrand.

You have no idea what has been shipped to Clermont Ferrand… a Lethal Weapon 2 container full of dollar bill wouldn’t even appear in the weird stuff shipped in Clermont Ferrand list, just because there’s regular containers of Euro Bills shipped there for destruction. ( the French print shop for Euros is in Chamalières, and the paper work is in Vic le Comte )…
So containers full of bills is somewhat common… ( I saw them enough on the motorway between Paris and Clermont Fd… and my mother got caught in the middle of a paper convoy once long ago [ when it was still Francs ], she was stuck there until they reached the print shop… she never drove through Clermont Fd that fast [ and since she was going higher in Chamalières it wasn’t a bother ] )

The weirdest thing ever shipped to Clermont Ferrand is a few barrels of Heavy Water ( all the Heavy Water in France and what came from from Norway ) along with their accompanying Nobel Prize owners.( and it was just part of their weird trip )

changedmynameasIworkinadealershipandsomeofourbrandsarentgreat
changedmynameasIworkinadealershipandsomeofourbrandsarentgreat
9 months ago

This is why I love the internet, reading stuff like this. My own weird stuff seen on the road (I think it was in the area: day 3 of a trip from nice to st Malo – wait just checked a map and we had stayed in Lyon the second night, first was Montelimar) 5 utterly blacked out Ferrari 360 modenas in a row bumper to bumper at speed when we were there in 1999). Guessing now it was related to Michelin

Ben
Ben
9 months ago

Betamax for the home consumer was deader than Jason’s RV (although it found a second life in professional broadcasting).

Pedant alert: Sort of, but not really. The thing that caught on for pro work was Sony’s Betacam which is similar but not the same as Betamax.

Obligatory plug for Technology Connections video on the matter: https://www.youtube.com/watch?v=hGVVAQVdEOs

ColoradoFX4
ColoradoFX4
9 months ago

“…who the fuck wants a notchback Fox body Mustang?”

Me, for one. A 1987-92 LX 5.0 notchback is on my bucket list of cars.

Goblin
Goblin
9 months ago

For what it’s worth, in their time, TRX tires were better all the way than anything else available – including in grip and handling. I remember a lenghty road test of some Alfa Romeo Sprint (or Alfasud, forgot) in the French revue Echappement (these were the guys who back then would take points off during a review if a car came with power windows because it added weight, and would get a special commitee to decide on a case by case basis whether power steering coming stock on a model is a plus or a minus, because – weight again 🙂 ), and they were explaining why and how the TRX’es transformed the car’s behavior at the limit (they were always driving at the limit). It wasn’t just a dark “Je suis French” thing, it was a real upgrade over everything else.

French drivers have always fascinated me with the way they nonchalantly drive like rallye drivers – all of them, beginners, experts and retirees – while keeping up a conversation, texting, or doing anything else we do at the wheel, just relying on the car being able to take it. If you want to kill an average French driver, just give them a wavy ondulating US suspension and let them on their daily commute.

So on a French road with a French driver (there is such a thing, for both, they DO drive in a spirited way on small twisty roads while listening to Mylene Farmer on the radio and croaking along with the song), a TRX, especially in the late seventies and all the way to the late 80’s, was a BIG difference.

There is no worse crime in technology than trying to add a new standard though, so it was what it was. Standard technology caught up, and the TRX is gone.

I still don’t consider TRX being a worse thing than the runflat tires still forced nowadays on many minivans and till recently – on many BMWs. Judging by the throves of threads in any BMW forum about “how do I get rid of runflats ?”, it’s pretty much the same issues. Except runflats drive like crap even when they work.

PS: Oh, important, how could I forget. Philips’ Video 2000 (v2000) was technologically the best format. Yes it was. The legend goes it cost 5x more than Betamax to manufacture. The allowed tolerances were at a whole different level. T’was but a little strike on the dark sky of the format wars 😛

Last edited 9 months ago by Goblin
Tim R
Tim R
9 months ago
Reply to  Goblin

As a relatively new BMW driver, <sigh>

JDS
JDS
9 months ago

Back in the early 90s, I dailied an ’84 BMW 533i. The first thing I did after I bought it was replace the factory TRX alloys for imperial wheels and new tires to replace the corded TRX’s that the previous owner had on it. Like others, I found a new set of imperial wheels and decent tires was less expensive than the TRX tires on their own — especially by ’94-95 when nobody but Michelin was making them.

No RIP, not sorry to see the TRX’s die. It was a solution in search of a problem.

Goblin
Goblin
9 months ago
Reply to  JDS

 It was a solution in search of a problem.”

Respectfully, nope. It was a solution for very real problems, in its time.
Standard tire technology did catch up, so TRX didn’t make it as a mounting standard, but it doesn’t make it less valid.

Not to mention that whatever research was done for the TRX also likely benefitted standard tire technology.

After all, a big chunk of the tires that made the TRX less attractive and economically non-viable were still Michelin tires 🙂

Speaking of which, Michelin TRX are still made, available, and sold – and benefitting from all the recent technologies. I wouldn’t bet the farm on how many TRX rims remain in good working condition thoough.

DrDanteIII
DrDanteIII
9 months ago

My dad won a 1988 BMW 535is in the BMW car club raffle. The “is” verison was the 2nd highest performance 5-series under the M5 at the time and came with the exotic TRX tires. Once the TRX’s wore out, he found it was cheaper to buy new wheels and tires in a normal size than it was to replace the TRX’s. And he OWNED a repair shop.

Bongo Friendee Harvey Park
Bongo Friendee Harvey Park
9 months ago

> 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.

If you people continue to write like this I’m going to need to stop being a cheap bastard and subscribe.

Bongo Friendee Harvey Park
Bongo Friendee Harvey Park
9 months ago

> 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

I hate to be a jerk but SWaG got the style too.

Bongo Friendee Harvey Park
Bongo Friendee Harvey Park
9 months ago
Reply to  Adrian Clarke

Come visit!

Freelivin2713
Freelivin2713
9 months ago

“The jerk store called, they’re runnin out of you!”
George Costanza

James Fairman
James Fairman
9 months ago

Get Image (UK) to make you some wheels. They are not that expensive and can usually make any size/offset you want. I have used them nay times for projects and they have a good retro catalogue of styles.

Try this one?

https://www.imagewheels.co.uk/billet-11-alloy-wheel/

ADDvanced
ADDvanced
9 months ago
Reply to  Adrian Clarke

Why? As a designer, use your design speak to communicate. I think the wheels look good but the ride height is bad, looks lifted. Those proportions are closer to the concept sketches tho, for sure.

FloridaNative
FloridaNative
9 months ago
Reply to  Adrian Clarke

Waddya mean?… that’s the nicest gen2 MR2 I’ve seen in a while.

ADDvanced
ADDvanced
9 months ago
Reply to  Adrian Clarke

Error 404 design critique not found.

Bongo Friendee Harvey Park
Bongo Friendee Harvey Park
9 months ago
Reply to  Adrian Clarke

What the f happened to the rear end?

Ranwhenparked
Ranwhenparked
9 months ago

Eh, we had both in the family growing up, the Beta player got moved to the basement at some point when we got a VHS for the living room, I can’t recall much perceptible difference between the two in picture quality, if there was, it was probably beyond what the TVs of the time could really display

IIRC, a bigger issue was run time, Beta launched with 1 hour max, VHS launched with a nominal 2 hours, extendable to 4 hours with increased speed, which let you record an entire NFL game. Later thin VHS tapes could hold up to 8 hours.

Sony eventually figured out how to get Beta to record 4 1/2 hours, but that was obviously still not close.

Their early machines were also both more expensive, but also less well featured for the money. So, you’ve got a picture quality difference, that, if it’s there, it’s too subtle to really notice, plus less features and less run time, but for more money. Yeah, it was real tough to see why Beta died and fast.

It seems like Sony initially assumed the bigger market was going to be pre-recorded tapes and didn’t really think about how much people might have wanted to time shift TV shows, but VHS was tailor made for time shifting out of the gate

Bongo Friendee Harvey Park
Bongo Friendee Harvey Park
9 months ago
Reply to  Ranwhenparked

Amusingly it wasn’t the last format war sony lost. They had proprietary memory sticks, and the minidisc also didn’t last very long.

Bongo Friendee Harvey Park
Bongo Friendee Harvey Park
9 months ago
Reply to  Adrian Clarke

Minidisc recorders typically compressed the audio, and back then compression technology wasn’t as good as it is today. If you wanted fidelity, you’d use ADATs, which you could chain up (synced via SMPTE iirc) and have 16, 24, or more tracks of uncompressed audio.

The ADAT and any other tape’s Achilles heel was the constant mechanical winding (be kind, rewind) that wore out components in the deck and the cassettes themselves, and was slower than instant seek on files stored on hard drive or RAM.

Isn’t if amazing you can record high fidelity 128-track audio on a laptop and store the entire thing on a micro SD card the size of a pinky nail, when a 24-track ADAT rig and cassettes took up a significant amount of floor space and weighed a ton.

DadBod
DadBod
9 months ago

but they won Blu-Ray!

UnseenCat
UnseenCat
9 months ago
Reply to  Ranwhenparked

The biggest visible difference between Beta and VHS was the picture quality during pause and fast-search forward and reverse. With VHS, until four-head models arrived later, the picture would degrade into a mess of lines and distortion in any mode other than normal playback. Beta offered pause and scan modes with a clear image. That made it particularly good for running the tape back and re-playing a particularly good spot from a recorded sports broadcast.

David Smith
David Smith
9 months ago
Reply to  UnseenCat

Or if you wanted to frame by frame through the nekkid scenes in movies Beta was infinitely better. (or so I heard)

Acid Tonic
Acid Tonic
9 months ago

Scrolled to see more details on the ferrari, left unsatisfied.

Phantom Pedal Syndrome
Phantom Pedal Syndrome
9 months ago

You’ve gone and hit me on the head with the nostalgia stick.
I grew up with that JVC VCR. So many Lego men launched off its top ejecting cassette holder, or trapped inside. Too many older siblings recording TV shows over movies.
I’m gonna watch “Breakin”.
Nope I guess not. I’m gonna watch the first half of “ Breakin” and then the last half of a random “Red Dwarf” episode followed by fifteen minutes of a dance recital.
My family’s VHS collection got very very confusing over time.

Jack Trade
Jack Trade
9 months ago

Family had the same VCR when I was a kid. The giant color-coded buttons were the best part.

Bonus: that model also appears in the opening credits of every The Goldbergs episode.

ADDvanced
ADDvanced
9 months ago

Alright, curious since you mentioned new wheels are in the future at some point; what’s your feeling on stancing this thing? And I don’t mean slammed to within a mm of it’s life with stupid camber angles, I mean lowering it so the wheels are centered in the wheel wells, and upsizing the diameter to fill them out and give the car better proportions.

Example:
https://youtu.be/VKPGKJm-WWk

IMHO, ‘tasteful’ modifications of wheel diameter, offset (flush w fender lip), and ride height (center wheel in wheel well) is THE designer’s way to modify a car, since the vehicle would be closer/more representative of the initial concept sketches, and the designers intentions. I’m sure you know as things go through production the engineers futz with all that stuff after focus groups say it rides too harsh, or the wheels cost too much, etc.

Thoughts?

ADDvanced
ADDvanced
9 months ago
Reply to  Adrian Clarke

Stock mondial = cool but not personal.

Mondial w better wheels & tasteful ride height tweak w maybe an exhaust = oh yeaahhhhh

Guarantee if you swap out the wheels you’ll want to drop it a bit as it will look ‘lifted’. Bigger diameter + stock ride height always just looks goofy. Maybe invite Gossin or Tracy over there for a trip and have him smash it out.

ADDvanced
ADDvanced
9 months ago
Reply to  Adrian Clarke

sweet! Post some clips of it… for like.. content.

Mike Smith
Mike Smith
9 months ago
Reply to  Adrian Clarke

This one running 225/55r16’s hits the right notes for me. https://medium.com/motorious/blue-and-gold-1985-ferrari-mondial-3f2aa1f6931a
It is interesting that those rims are only 3/4″ bigger than the ‘390’ rims on yours – they visually have a lot more weight.
I also wonder if that one is lowered – if it is, it is only very modestly so. Tastefully done IMO.

Last edited 9 months ago by Mike Smith
Daniel MacDonald
Daniel MacDonald
9 months ago

My ’83 BMW 533i came with TRX originally, a previous owner swapped to P-Metric 15″ wheels from a 735i onto it, but somehow it still has the original TRX spare-and it holds air though I’d be afraid to put miles on it.

Paul E
Paul E
9 months ago

Saab also used TRX on high-level 1979-80 900 Turbos – the five-door variant in the US market… the three-door cars still used the “Inca” wheels, as found on the original 99 Turbo.

Sean Hannay
Sean Hannay
9 months ago

My father bought an ‘88 BMW M6 in 1990 that had its original TRX wheels and tires on it. Got ditched for a set of standard BBS RS wheels at the first tire change.

Rapgomi
Rapgomi
9 months ago
Reply to  Sean Hannay

I had a 633CSI with BBS wheels… The factory TRX wheels came with in boxes, and they went with it in boxes when I sold the car several years later.

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