M3 WEARS specially developed 18-inch tyres measuring 225/45 ZR18 up front and wider 255/40 ZR18 at rear. Those on our test vehicle were Continental ContiSport Contact tyres, riding on eight-inch, 20-spoke alloys up front and nine-inch items at the rear. The double-spoke design makes for difficult cleaning, but a touch of class is the steel valve caps. Interestingly, there is no spare wheel and no jack. In their place is the second generation M Mobility system, which can seal holes in tyres up to 6mm in diameter via a compressor and fluid injection. BMW says the system allows M3 drivers to continue travelling (at reduced speed) after a puncture without changing wheels, and that the lack of a spare wheel saves more than 20kg. The M Mobility system is complimented by BMW's tyre pressure warning system (TPW), which permanently monitors each tyre's rolling circumference and sounds an alarm when pressure loss exceeds 50 per cent.