How this new tyre can keep you going - even with a six-inch nail stuck into it
Mondell: Road tested - Bridgestone DriveGuard
When an engineer invites you to negotiate a slalom course on a tyre that has just had a six-inch nail driven into it, you wonder if the laws of physics have been overturned.
Ever since the invention of the pneumatic tyre, punctures have been an unwelcome risk for motorists.
Over a four-year period, the average driver has a 60pc chance of suffering a flat tyre.
In the old days you'd rummage in the boot for the spare, and either change the punctured wheel yourself or rely on a passing motorist to come to your aid.
Nowadays though, it's increasingly rare for new cars to be supplied with full-size spare wheels as manufacturers try every trick to save weight and improve emissions figures.
There might be a skinny space-saver tyre provided, or more likely a mobility kit, but surveys show that neither option presents peace of mind to motorists that they will get them home safely.
Even if there is a spare wheel to hand, it seems fewer of us want to get our hands dirty. According to tyre company Bridgestone, one-in-three men and up to 72pc of women aren't willing to undertake a wheel change.
That's why Bridgestone's new DriveGuard tyre might just be tapping into the zeitgeist of the moment. Launched here recently, it allows a driver to continue driving safely after a puncture for up to 80km at speeds of up to 80kmh.
Run-flat tyres have been around for years, but only in specific sizes and where car manufacturers offer them as original equipment.
DriveGuard is the first run-flat that can be fitted to all cars provided the vehicle is equipped with a Tyre Pressure Monitoring System (TPMS) - a standard feature on all new cars since 2014.
When punctured, thicker sidewalls support the weight of the vehicle, while a special cooling fin design and advanced polyester carcass body ply prevent the tyre overheating.
A further safety benefit is that you're less likely to lose control by experiencing a full tyre blow-out. Whether or not the tyre can be repaired will depend on the damage. Bridgestone is being understandably cautious, saying in most cases a replacement will be necessary.
Driving on a punctured tyre, you're aware it isn't correctly inflated, particularly when cornering (surely a good thing), but it feels perfectly safe to drive. Impressively, when you take your hands off the steering wheel, the car runs straight and true.
Bridgestone here say the DriveGuard tyres will cost around 15pc more than equivalent regular tyres. That's a premium well worth paying if it gets you to your destination safely.