A Dodge Charger factory drag racer on Hoosier drag radials. Picture: Dodge

Durban - Whether or not you're a drag racing fan, you'll have seen competitors taking the wheels off their cars and slapping on a 'chunkier' set, usually with higher-profile tyres that have little or no tyre thread pattern. These tyres are known as 'drag radials', 'slicks' or 'semi-slicks' - but why don't the drivers of these cars just leave these wheels on and drive with them to the track?

The problem is that drag radials only work on dry surfaces - and only when they're hot, which is why the racers deliberately spin their wheels in a short 'burnout' before they line up for a race. That's to get as much heat as possible into the tyres, for maximum traction.

If they drive with those tyres on the street, they'll have amazing grip - as long as conditions are perfect, dry and clear. But the moment they encounter rain, a tiny oil patch, a puddle or anything other than dry tarmac, the car could lose traction and the driven wheels would spin uncontrollably.

Drag radials have appallingly poor traction under any conditions other than warm, completely dry weather; anybody who has made the mistake of driving on drag radials in the rain and survived to tell about it will tell you that the car is almost always completely out ofcontrol on wet roads.

Maximum surface contact

That's because drag radials are designed to create maximum surface contact between rubber and tarmac, with no sipes or tread pattern to channel water away from the contact patch - with the result that using drag radials in wet weather is very much like trying to walk on ice in smooth-soled shoes. You'll get little or no traction as the tyres simply slide across the wet tar.

Another reason not to use drag radials on the street is that they're made from a very soft rubber compound that that wears very quickly, so they won't last more than a few weeks or months in daily use - and they cost a fortune to replace.

If you come across the words 'Hoosier' or 'Mickey Thompson' (two specialist manufacturers of drag radials) written in white on the side of a car's tyres at a drag meeting, you should generally assume that one of those tyres cost more than all the tytres ese wheels costs more than all four wheels on your car, include the fifth spare wheel for good measure.

Motoring.co.za

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