Page 288 - Automotive Engineering Powertrain Chassis System and Vehicle Body

Tyres and wheels C HAPTER 10.1

Fig. 10.1-9 If they have the same outside diameter and load capacity the four tyre sizes used on medium-sized passenger cars are
interchangeable. The series 65, 55 and 45 wide tyres each allow a 1’’ larger rim (and therefore larger brake discs). The different widths and
lengths of the tyre contact patch, known as ‘tyre print’, are clearly shown (Fig. 10.1-19), as are the different designs of the standard
road profile and the asymmetric design of the sports profile (see also Section 10.1.2.10). The 65 series is intended for commercial
vehicles, and the 60, 55 and 45 series for sports cars. (Illustration: Continental; see also Fig. 10.1-19.)
The old markings can still be found on individual
tyres:
155 S R 13
rim diameter in inches

radial tyre

–1
speed symbol (authorized up to 180 km h )
width of the new tyre and 82 series, when details of
the cross-section ratio missing

–1
10.1.2.5.2 Designations of US tyres and 240 km h , Fig. 10.1-12); the size used by Porsche on
discontinued sizes for passenger cars the 928 S can be used as an example:
Tyres manufactured in the USA and other non-European
countries may also bear a ‘P’ for passenger car (see
Fig. 10.1-17) and a reference to the cross-section ratio: 225/50 VR 16
radial tyre
P 155/80 R 13 79 S
The old system applied up until 1992 for tyres which speed symbol V
–1
were authorized for speeds of over V ¼ 210 km h –1 (or (authorized over 210 km h )

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