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, a directional coordinate in a polar coordinate system
* Radial set
* A bearing f ...
tire
A tire (American English) or tyre (British 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 (engineering), t ...
introduced by the
Michelin
Michelin (; ; full name: ) is a French multinational tyre manufacturing company based in Clermont-Ferrand in the Auvergne-Rhône-Alpes ''région'' of France. It is the second largest tyre manufacturer in the world behind Bridgestone and la ...
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, as in its logo) is a consumer-level analog recording and cassette format of magnetic tape for video, commonly known as a video cassette recorder. It was developed by Sony and was released in Japan on May 10, 1975, ...
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
![1995 BMW 525i Sport, UK (rear) (22286662269)](https://upload.wikimedia.org/wikipedia/commons/6/6e/1995_BMW_525i_Sport%2C_UK_%28rear%29_%2822286662269%29.jpg)
TRX tires were available either as standard or optional equipment on certain models of European makes such as
BMW,
Audi
Audi AG () is a German automotive manufacturer of luxury vehicles headquartered in Ingolstadt, Bavaria, Germany. As a subsidiary of its parent company, the Volkswagen Group, Audi produces vehicles in nine production facilities worldwide.
Th ...
,
Mercedes-Benz
Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquartere ...
,
Citroën
Citroën () is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded in March 1919 by André Citroën. Citroën is owned by Stellantis since 2021 and previously was part of the PSA Group after Peugeot acquired ...
,
Peugeot
Peugeot (, , ) is a French brand of automobiles owned by Stellantis.
The family business that preceded the current Peugeot companies was founded in 1810, with a steel foundry that soon started making hand tools and kitchen equipment, and the ...
,
Ford
Ford commonly refers to:
* Ford Motor Company, an automobile manufacturer founded by Henry Ford
* Ford (crossing), a shallow crossing on a river
Ford may also refer to:
Ford Motor Company
* Henry Ford, founder of the Ford Motor Company
* Ford F ...
,
Ferrari
Ferrari S.p.A. (; ) is an Italian luxury sports car manufacturer based in Maranello, Italy. Founded by Enzo Ferrari (1898–1988) in 1939 from the Alfa Romeo racing division as ''Auto Avio Costruzioni'', the company built its first car in ...
,
Alfa Romeo
Alfa Romeo Automobiles S.p.A. () is an Italian luxury car manufacturer and a subsidiary of Stellantis. The company was founded on 24 June 1910, in Milan, Italy. "Alfa" is an acronym of its founding name, "Anonima Lombarda Fabbrica Automobili." ...
,
Renault
Groupe Renault ( , , , also known as the Renault Group in English; legally Renault S.A.) is a French multinational automobile manufacturer established in 1899. The company produces a range of cars and vans, and in the past has manufactured ...
, and
SAAB
Saab or SAAB may refer to:
Brands and enterprises
* Saab Group, a Swedish aerospace and defence company, formerly known as SAAB, and later as Saab AB
** Datasaab, a former computer company, started as spin off from Saab AB
* Saab Automobile, a fo ...
. They were also available on certain models of the
Ford Mustang
The Ford Mustang is a series of American automobiles manufactured by Ford. In continuous production since 1964, the Mustang is currently the longest-produced Ford car nameplate. Currently in its sixth generation, it is the fifth-best selli ...
, Ford Thunderbird,
Mercury Capri
Capri (later Mercury Capri) is a nameplate marketed by the Lincoln-Mercury division of Ford Motor Company on three distinct series of automobiles between 1970 and 1994.
From 1970 to 1978, the Capri was a sport compact marketed in North America ...
, Mercury Cougar, and
Mercury Lynx
The North American version of the Ford Escort is a range of cars that was sold by Ford from the 1981 to 2003 model years. The direct successor of the Ford Pinto, the Escort also largely overtook the role of the European-imported Ford Fiesta as ...
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 by British Leyland (BL) and, later, the Rover Group from 1980 to 1998. It was launched in 1980 as the Austin mini Metro. It was intended to complement and eventually replace the ...
* 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
The Citroën BX is a large family car which was produced by the French manufacturer Citroën from 1982 to 1994. In total, 2,315,739 BXs were built during its 12-year history. The hatchback was discontinued in 1993 with the arrival of the Xantia, ...
,
Peugeot 305
The Peugeot 305 is a medium-sized car produced by the French automaker Peugeot from 1977 to 1989. It was offered as a four-door saloon, five-door estate, and as a three-door van body derivative.
History
Origins
During the mid 1970s, the motoring ...
* 180/65 HR 390 TRX
SAAB 900 S and
Turbo
In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pr ...
(1980/81)
* 190/65 HR 390 TRX
Citroën CX,
Ford Granada, Mercedes 200, 220, 240,
Peugeot 504 Coupé,
Renault 30TX
* 190/55 VR 340 TRX
Alpine A310 V6 (AV),
Renault 5 Turbo
The Renault 5 Turbo or R5 Turbo is a sport hatchback automobile launched by the French manufacturer Renault at the Brussels Motor Show in January 1980. The car was primarily designed for rallying, but was also sold in a street version.
A total o ...
(AV),
Alfasud Ti
* 210/65 VR 365 TRX
Talbot Tagora SX
* 220/55 VR 365 TRX
Alpine A310 V6 (AR),
Renault 5 Turbo
The Renault 5 Turbo or R5 Turbo is a sport hatchback automobile launched by the French manufacturer Renault at the Brussels Motor Show in January 1980. The car was primarily designed for rallying, but was also sold in a street version.
A total o ...
(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, 728, 535, 635 Csi, 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
A convertible or cabriolet () is a passenger car that can be driven with or without a roof in place. The methods of retracting and storing the roof vary among eras and manufacturers.
A convertible car's design allows an open-air driving expe ...
,
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 “young-timer” replacements for vehicles which were originally fitted with them. As of 2014, Michelin Classic was producing these tires in 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