BMW defends adoption of run-flat tyres on new X5

BMW has dismissed claims its second-generation X5 luxury SUV, the world’s first SUV to run exclusively on run-flat tyres, will not be as capable off-road as its predecessor.

Some off-road experts have suggested that because run-flat tyres cannot be deflated, as is common practice in off-road situations to increase traction, they will offer even less grip than the current X5’s road-oriented rubber.

But BMW says there’s no reason why the forthcoming X5, which for the first time will employ "safety tyres" (as BMW’s fourth-generation puncture-resistant tyre will be labelled) will not be as good as its predecessor off-road - and is adamant its all-new luxury SUV offers greater on-road performance without reducing its ability away from tarmac.

The company says that few X5 owners actually venture off-road and, during run-flat discussions that dominated conversation at the E92 3 Series Coupe launch, produced figures to defend its controversial trend towards away from full-size spare wheels.

A space-saving "emergency" spare wheel is standard on 5 Series and is an option with both BMW’s 1 Series hatch and 3 Series sedan (BMW’s first volume-selling model to offer no spare tyre as standard).

Similarly, a so-called Space Saver Spare and Jack Pack is available as an accessory for the E92 3 Series Coupe, priced at $561 and comprising a space-saver spare wheel and tyre, tyre cover and jack kit.

As with 1 Series and 3 Series sedan, the purpose-built tyre cover is expandable, can accommodate alloy wheels of up to 19-inch in diameter and is designed to be secured within the boot via adjustable straps that attach to the four in-vehicle luggage hooks. An optional repair kit that comprises a compressor and sealant is also available for $220.

While 1 Series hatch and 3 Series sedan and coupe buyers must pay extra for a space-saver that robs boot space, both 5 Series and the forthcoming X5 offer a space-saver as standard – and a wheel well beneath the boot floor to accommodate it.

However, the new X5 won’t be available with a full-sized spare wheel, which is optional on the Mercedes-Benz M-class.

BMW’s head of corporate communications Toni Andreevski, who filled a similar role at DaimlerChrysler before July, says this is not an issue because only six M-class buyers had taken up this option – and that just 64 per cent of new cars sold in August came with a full-sized spare.

"About 20,000 new cars were sold last month without a full-size spare," he said, adding that Mercedes-Benz and Audi models employ run-flat tyre technology in Europe but their Australian subsidiaries instead fit space-savers as standard for marketing reasons.

"Because BMW is the only company that does, we get singled out," he said. "For the vast majority of people, this is a much safer and more convenient option. Customers want mobility and safety, and safety tyres are 100 per cent better on both counts."Mr Andreevski said the difference in ride quality between run-flats and conventional tyres was "negligible", that BMW was "overcoming" the lack of availability of run-flat tyres (which can be replaced with conventional tyres if necessary) and that the average price premium over conventional tyres was between $30 and $50.

He stressed that all BMW vehicles fitted with run-flats come standard with a tyre-pressure indicator, which warns the driver of any pressure loss greater than 30 per cent, and that 85 per cent of punctures result in a slow leak.

The vehicle may then be driven for 2000km at speeds of up to 80km/h, and for a further 250km only once fully deflated - at which point it must be replaced. After being fitted, most space-savers are limited to speeds of up to 80km/h for a distance of 250km.