Michelin TRX

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BMW E28 with Michelin TRX rims and tires

Michelin TRX is a system of radial tires introduced by Michelin in 1975 . It was developed in order to be able to consistently use the possible advantages of the radial tires first introduced in 1948, which was made possible by a system of tires and specially developed rims .

Features and benefits

The aim of the development was to evenly distribute the tension on the carcass; hence the name TRX is derived (TR for Tension Répartie , German for "distributed tension"). For this purpose, novel rims with lower rim flanges have been developed. The special shape of the rim and tire resulted in a smaller curvature of the tire flank in only one direction, i.e. not the S-shape of previous tire designs. This also increased the useful tire flexibility. Due to the lower and outward-facing contour of the rim flange, the tire has less grip on the rim under air pressure than with conventional rim shapes. To prevent the tire from slipping outwards, the TRX tires were provided with a circumferential bead on the inside of the rim seat, which prevented them from sliding outwards.

Advantages in terms of driving behavior compared to conventional radial tires included:

  • better road grip due to the more even pressure distribution on the tread,
  • greater comfort thanks to the more efficient use of tire flexibility.

Compatibility and dimensions

Since only tires with a safety bead sit securely on the TRX rim, conventional tires had to be prevented from being mounted on a TRX rim (and vice versa). This is why the TRX system was given a diameter that conventional tires and rims do not have. On this occasion the metric system was used immediately (340, 390 or 415 mm, about 12.4, 15.4 or 16.3 inches). The tire width is specified as a multiple of ten (for example 190 mm) and thus also differs from conventional tires, which are for example 185 or 195 mm wide.

commitment

TRX wheels were often used for different variants of the Citroën CX as well as the 604, 505 and 504 series from Peugeot . They were also available as special equipment for the BMW 6 Series Coupé, the BMW 3 Series , the 5 Series and 7 Series sedans, the Alfasud Ti Quadrifoglio verde and the Alfa Romeo Sprint , the Ford Granada , Renault R5 Turbo , the Ferrari 400 , the Jaguar XJ and Saab 99 / 900 offered. In addition, there were of BBS and Treser wheels for VW, Audi, Mercedes and others, also for TRX tires were designed.

In racing, the TRX system was successfully used in Formula 1 ( e.g. Benetton ) and in the World Rally Championship ( Audi quattro , Peugeot 205 Turbo 16 ).

Availability today

TRX tires are still available. At Michelin they are listed as vintage tires. They are not produced continuously, but only for a few weeks a year. Therefore, joint procurement campaigns are occasionally organized in groups of enthusiasts. The prices are extremely high. To save money, many classic car owners use conventional rims (and tires) instead of TRX rims.

other producers

Other manufacturers have also produced TRX tires. However, they were not allowed to use the term "TRX" as it enjoys trademark protection. These tires can be recognized by their dimensions.

Individual evidence

  1. ↑ a b c d TRX, the first low profile tire. Michelin, accessed July 19, 2020 .

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