dunlop run-flat tyres
Dunlop Aim To Make Carrying A Spare Tyre A Thing Of The Past Thanks To Their Latest Range Of Run-Flat Tyres. Andy Enright Puts Some To The Test
Coming second in the scary stakes to dumping an ex-girlfriend who had four rather large brothers was the occasion when I was forced to change a tyre late one wet Friday night on the hard shoulder of the M25. As my numb hands battled with a recalcitrant scissor jack, the front bumpers of articulated trucks were zinging past inches from my backside, jet washing me with grit and water.
As I stamped on the wheel brace to dislodge one of the wheel bolts, the thing popped off and sat a couple of feet away in the inside lane of the motorway. Reaction told me to reach for it but that very second it was sent clattering up the carriageway by 40 tonnes of truck. After eventually putting the space saver spare tyre on, I was then faced with the question of what to do with the filthy wet wheel and tyre. It eventually sat on the rear seats and the stains have never come out of the suede trim. Not how I envisaged spending that particular Friday night and not an experience I'd like to repeat.
A far safer option would have been to drive the car somewhere safe and well-lit and conduct the job in safety. This, however, would require a tyre that could be driven some distance with no air on board. Dunlop, the inventors of the pneumatic tyre, now have just such rubberwear available to the likes of us. The Dunlop DSST (Dunlop Self Supporting Tyre) has been developed to offer customers a tyre that doesn't require any special wheels, sticky foams or specialist fitting requirements. Unlike the rival Michelin system, which necessitates the use of special wheels with a thick rubber block running around their circumference, the Dunlop DSST gets around the issue of heat build up by using a patented system that comprises a special sort of very rigid rubber in the tyre sidewall. This means that even if the tyre is completely flat, it will still bear the car's weight without the wheel rim coming into contact with the ground, even during cornering manoeuvres.
We decided to test Dunlop's claims for ourselves and fitted a BMW 1 Series with a set of four Dunlop DSST boots. In order to get a feel for the tyres, we ran a number of laps of the test track withal four tyres fully inflated first, and then asked a technician to replicate a catastrophic puncture scenario by drilling an 8mm hole into the sidewall of the tyre using an electric drill. With the tyre completely devoid of anything but atmospheric air pressure, it was a strange feeling to pull away. There was a very slight pull to one side when driving in a straight line but certainly nothing to concern us. The tyre made a good deal of noise when cornering, which was a little disconcerting at first, but once one had got used to the feel of the deflated tyre, it was possible to push it a little bit harder to try to get it to misbehave.
Dunlop quote a range of 50 miles at a top speed of 50mph - more than enough to get you either home or to a safe place - but we decided to see if they could handle a little more in the way of speed. After deflating the three other tyres and heading out onto the test track with a full quartet of flats, we saw speeds in excess of 100mph on the start/finish straight and cornered the car with absolutely no finesse whatsoever in an attempt to tear the tyres from the rims. Nothing we did would upset the tyres. I even jerked the steering wheel onto full lock at over 70mph and the tyres just doggedly ploughed on. Deeply impressive stuff. The feel of the car when it rolled onto the sidewalls and then popped back up onto the tread blocks at the exit of corners felt a little odd but at no time did it ever feel marginal in terms of safety.
The advantages of run-flat tyres are easy to appreciate. Aside from the issue of not having to change tyres by the side of a busy motorway or in an unsavoury part of town, it also means that cars like today's MINI, which can feature wheels up to 18 inches in diameter, are now relieved of the problem of where to fit the spare. Less weight, more luggage space and greater safety are other obvious side effects. An increasing number of manufacturers are fitting the Dunlop SST system as standard. The company is supplying SP Sport 01 tyres with DSST technology to BMW in 17 and 18-inch sizes for fitment of the latest 5 Series. Run-flat versions of SP Sport Maxx TT, SP Sport Fastresponse and SP Sport Maxx GT are also available in the Dunlop range of tyres.
Sales of run-flat tyres have risen tenfold over the past three years. It seems as if it really is time to shed our spare tyres at last.