Bridgestone offers a new spin on 'runflats'

Nice, France – Bridgestone has launched a new extended mobility tire for the European region, which it claims is a "game-changer" for the replacement market.

Amid much pre-launch fanfare at a press launch in Nice, however, it emerged that the tire was a version of DriveGuard tire introduced in the North American market two years ago.

The tire does, though, feature a combination of technologies that could justify at least some of the hype and the high hopes expressed by Bridgestone officials for the product.

DriveGuard, which can be driven in deflated condition at 80km/hr for 80km, is being billed as a premium touring tire with the added bonus of extended mobility and, hence, safety - rather than a ‘runflat’.

While runflats are generally supplied as optimised factory fitments, the new tire can be fitted to most cars equipped with tire pressure monitoring systems (TPMS) devices – mandatory on new cars in Europe since November 2014.

The product, added Bridgestone, offers higher performance ratings than conventional runflats under the EU tire labelling scheme: it carries an A rating for wet grip performance and C rating for rolling resistance.

At the heart of this performance is a treated polyester fibre reinforcement that, said Bridgestone, overcomes the ride-comfort issues which have limited the uptake of runflats to a niche segment of the market over the past 15 years.

The polyester fibre is treated with a coating material developed by Bridgestone to help ensure that reinforced sidewall supports the vehicle upon sudden air loss

This treatment enables the polyester, which has a softening point of around 140 degrees C, to withstand the deflated driving conditions, when temperatures within the rubber can rise to 180-200 degree C.

The reinforcement technology also allows the use of thinner rubber layers to further enhance the ride performance of the extended mobility tire – while durability and rolling resistance are enhanced by the use of an optimised nano-filler/compound system.

Another design feature is the use of sidewall ribbing or ‘cooling fins’ that can reduce sidewall temperatures by 20 degrees C: channelling heat away to the tire rim when driving on a deflated tire.

Unlike the all-season version launched in North America, European drivers will be offered summer and winter Driveguard tires – more attuned to the wet driving and cornering conditions experienced in the region.

DriveGuard, which is being manufactured at Bridgestone's Poznan plant in Poland, will be available in 19 summer and 11 winter sizes – from 185/65 R15 up to 245/40 R18.

The summer tire will be available from March in much of Europe from March with sales of the winter tire to follow in June, according to a Bridgestone spokesman.

Due to capacity issues, customers in Scandinavia and eastern Europe will not be offered the product until next year, the spokesman also pointed out.