The Michelin TRX, (and the related TDX), is a
radial
Radial is a geometric term of location which may refer to:
Mathematics and Direction
* Vector (geometric), a line
* Radius, adjective form of
* Radial distance (geometry), a directional coordinate in a polar coordinate system
* Radial set
* A ...
tire
A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineeri ...
introduced by the
Michelin
Michelin ( , ), in full ("General Company of the Michelin Enterprises P.L.S."), is a French multinational tyre manufacturing company based in Clermont-Ferrand in the Auvergne-Rhône-Alpes '' région'' of France. It is the second largest t ...
Group in 1975. It is one of the first volume-produced low-profile tires. Although technologically advanced, and reasonably successful, the tire's requirement for a non-standard
rim ultimately condemned it to a relatively short commercial life. It has thus been called the "
Betamax
Betamax (also known as Beta, and stylized as the Greek letter Beta, β in its logo) is a discontinued consumer analog Videotape, video cassette recording format developed by Sony. It was one of the main competitors in the videotape format war ag ...
of the tire industry.
"
Background and development
As passenger car performance increased during the 1970s, the need arose for improved tire capability. One of the possibilities was to reduce sidewall height, low sidewalls being common at the time on crossply racing tires, but not usual for the better-performing radial tire. The problem was that reducing sidewall height compromised tire comfort, in part due to the roadwheel rim profile used.
Michelin therefore decided to introduce the world's first tire and roadwheel system, where the two were designed together. This would enable both lower sidewall height, (for better roadholding) whilst retaining comfort due to better stress distribution within the tire, enabled by the redesigned wheel rim and tire bead.
The "TR" was for "tension répartie", since tire stresses were better balanced in the new design, whilst the "X" was a reference to previous Michelin products such as the famous "X" radial.
TRX tires thus require the use of wheels that were specially designed for them; standard tires do not fit TRX wheels and vice versa.
To avoid potentially dangerous confusion, Michelin used metric sizes for TRX roadwheels instead of the standard imperial wheel size (normally stated in inches).
Usage
TRX tires were available either as standard or optional equipment on certain models of European makes such as
BMW
Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...
,
Audi
Audi AG () is a German automotive manufacturer of luxury vehicles headquartered in Ingolstadt, Bavaria, Germany. A subsidiary of the Volkswagen Group, Audi produces vehicles in nine production facilities worldwide.
The origins of the compa ...
,
Mercedes-Benz
Mercedes-Benz (), commonly referred to simply as Mercedes and occasionally as Benz, is a German automotive brand that was founded in 1926. Mercedes-Benz AG (a subsidiary of the Mercedes-Benz Group, established in 2019) is based in Stuttgart, ...
,
Citroën
Citroën ()The double-dot diacritic over the 'e' is a diaeresis () indicating the two vowels are sounded separately, and not as a diphthong. is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded on 4 June 19 ...
,
Peugeot
Peugeot (, , ) is a French automobile brand owned by Stellantis.
The family business that preceded the current Peugeot companies was established in 1810, making it the oldest car company in the world. On 20 November 1858, Émile Peugeot applie ...
,
Ford,
Ferrari
Ferrari S.p.A. (; ) is an Italian luxury sports car manufacturer based in Maranello. Founded in 1939 by Enzo Ferrari (1898–1988), the company built Auto Avio Costruzioni 815, its first car in 1940, adopted its current name in 1945, and be ...
,
Alfa Romeo
Alfa Romeo Automobiles S.p.A. () is an Italian carmaker known for its sports-oriented vehicles, strong auto racing heritage, and iconic design. Headquartered in Turin, Italy, it is a subsidiary of Stellantis Europe and one of 14 brands of mu ...
,
Renault
Renault S.A., commonly referred to as Groupe Renault ( , , , also known as the Renault Group in English), is a French Multinational corporation, multinational Automotive industry, automobile manufacturer established in 1899. The company curr ...
, and
SAAB. They were also available on certain models of the
Ford Mustang
The Ford Mustang is a series of American Car, automobiles manufactured by Ford Motor Company, Ford. In continuous production since 1964, the Mustang is currently the longest-produced Ford car nameplate. Currently in its Ford Mustang (seventh ...
, Ford Thunderbird,
Mercury Capri
Capri (later Mercury Capri) is a Nameplate (automotive), nameplate marketed by the Mercury (automobile), Lincoln-Mercury division of Ford Motor Company over three generations between 1970 and 1994.
From 1970 to 1978, the Capri was a sport compact ...
, Mercury Cougar, and
Mercury Lynx during the 1980s.
Although most TRX tires were produced by Michelin, a few sizes were made by Avon, Continental, Goodyear (mainly for the American market
) and Dunlop. Dunlop fitted their version of the TRX tire as standard equipment on Austin Montegos and Austin Mini Metros.
TRX sizes
TRX wheels existed in diameters from to
Some common TRX sizes and vehicles:
Size Application
* 160/65 R 315 TRX
Innocenti Turbo De Tomaso (1984-1989),
Austin Metro
The Metro is a supermini car, later a city car that was produced from 1980 to 1998, first by British Leyland (BL) and later by the Rover Group. It was launched in 1980 as the Austin Mini Metro (styled AUSTIN miniMETRO).
The Mini Metro was inte ...
* 160/65 SR 340 TRX
Citroën Visa GT
* 165/70 R 365 TRX Ford Escort GT, EXP, Mercury Lynx RS
* 170/65 R 365 TRX
Citroën BX,
Peugeot 305
* 180/65 HR 390 TRX
SAAB 900 S and
Turbo
In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the ...
(1980/81)
* 190/65 HR 390 TRX
Citroën CX
The Citroën CX is a large, front-engined, front-wheel-drive executive car/luxury car manufactured and marketed by Citroën from 1974 to 1991. Production models were either a standard wheelbase or a stretched, more luxurious, four-door fastback ...
,
Ford Granada, Mercedes 200, 220, 240,
Peugeot 504 Coupé,
Peugeot 505
The Peugeot 505 is a large family car produced by the French manufacturer Peugeot from 1979 to 1992 in Sochaux, France. It was also manufactured in various other countries including Argentina (by Sevel from 1981 to 1995), China, Thailand, Indon ...
,
Peugeot 604,
Renault 30TX
* 190/55 VR 340 TRX
Alpine A310 V6 (AV),
Renault 5 Turbo (AV),
Alfasud Ti
* 210/65 VR 365 TRX
Talbot Tagora SX
* 220/55 VR 365 TRX
Alpine A310 V6 (AR),
Renault 5 Turbo (AR)
* 200/60 VR 390 TRX BMW 518, 520, 525, 528, 728, Mercedes 200, 220, 240, 300
* 210/55 VR 390 TRX
Citroën CX 25 GTI Turbo
* 220/55 VR 390 TRX BMW 525, 528, 533i, 535, M535I, 635 Csi, 728, 735i.
Ford LTD Ford Mustang, Thunderbird. Mercury Capri, Cougar. Ferrari 208, 308,
Mondial 3, 2 (AV)
* 240/55 VR 390 TRX
Ferrari Mondial 8 &
Cabriolet,
Mondial 3, 2 (AR)
* 240/55 VR 415 TRX
Ferrari 400 i, 512 B,
412 i
* 240/45 ZR 415 TRX
BMW M635 CSi, Ferrari 512 BB (AV),
Testarossa (AV)
* 280/45 VR 415 TRX Ferrari 512 BB (AR),
Testarossa (AR)
Note: AV='front', AR='rear'. Does not include North American vehicles.
Other sizes were available, for instance 160/65 R 315, in TDX version.
Decline
Although the tire gave good performance, and thus as noted above gained favour with some OEMs, its non-standard dimensions proved problematic in the aftermarket. It was also a notoriously hard tire to remove when using basic tools, a consequence of the deliberately designed strong fit between tire bead and rim.
Rival manufacturers, such as Dunlop, thus produced replacement wheels and tires for popular cars, specifically for high-performance or winter conditions.
In due course advances in tire technology caught up with the TRX line, enabling similar performance and greater convenience at lower cost. TRX tires are now produced only as replacements for vehicles which were originally fitted with them. As of 2024, Michelin Classic is producing these tires in its catalogue.
References
Citations
External links
TRX page from Michelin Group website
Independent history and review of the TRX tire.Article on TRX tires for SAAB automobiles.
{{primary sources, date=June 2007
Michelin brands
Tires