Friday 17 November 2017

How drivers are hanging on to life by a bare tread

The difference in performance between budget and premium tyres, and in tyres of different depths, on wet roads is astounding, writes Geraldine Herbert

Geraldine Herbert

Geraldine Herbert

THUNDERING towards a hair-pin bend, I was abruptly reminded of the importance of a decent set of tyres. As the back end of the car began to slide and the wheels spin, I was relieved that this was not a public road but a test facility for tyres in Germany.

From wet and dry handling circuits to a race track, Contidrom is where Continental tests the performance of tyres on a range of wet, dry and icy conditions. And testing tyres in wet conditions was why I was there, in particular to see first hand the difference between budget and premium.

In the current climate, it's no surprise that many motorists shop on price and not quality. New legislation on tyre labelling has made it easier for motorist to compare tyres. Tyres are now labelled from A (Best) to G (Worst) with information about performance grades on fuel efficiency, wet braking and external noise levels all clearly displayed.

Prices can vary by as much as €20-€80 for a budget versus premium tyre. But with up to 225 days of rain here each year, a tyre that can handle wet conditions is vital. Imported tyres from China and Taiwan may cost less than premium tyres but are they as good?

To find out, we had the opportunity to drive a BMW120i fitted with E rated budget tyres and another with Premium A rated. Given the fact that these are identical cars with the same braking and traction control systems, the results are astounding. The car with budget tyres had essentially no grip, and threatened to spin out of control at every corner. Even at low speeds, it was virtually impossible to maintain a constant road position. Driving the same car fitted with premium tyres was a totally different experience. It came as no surprise that the premium tyres are better; the eye-opener is by how much. It drove like a totally new car. At high speed it was composed and cornered with ease. The difference between both cars was simply the choice of tyres.

Next up was the question of mixing budget and premium tyres. Tyres are normally replaced in pairs and very often the new ones are put to the front of the car and the old ones to the rear. This raises the question of whether it matters if you mix premium and budgets tyres or even more crucially should they be fitted to the front or to the rear?

To find out, we drove three Mini Coopers fitted with a different mix of budget and premium tyres. The first was fitted with premium tyres worn down to 4mm at the front, and new budget tyres at the rear, with the full 8mm of tread.

Another Mini had the same set up but in reverse so the budget tyres were to the front. The last Mini was fitted with 4mm and 8mm Continental tyres on the front and back.

The Minis were driven around a tight circular circuit designed to mimic a roundabout or a motorway exit.

The Mini with the new but budget tyres to the rear was fine at speeds below 45km but at any higher speed, the budget tyres at the rear struggled for grip. In contrast, the Mini fitted with budget tyres to the front and premium to the back was far more composed and was stable and safe at speeds up to 50km. While it was the best of the budget options, at any speed in excess of 50km, there was a serious loss of stability.

Finally the predictable handling of the Mini fitted with 4mm and 8mm premium tyres on the front and back illustrated clearly that if you are only buying two new tyres, they should be mounted at the back.

The final and most alarming test was the one for tyre depth. To assess how much the level of grip in a tyre deteriorates as the tread wears, we tested three identical Volkswagen Golfs on a wet surface. Each was fitted with Continental tyres. The first, with 8mm of tread, the second with 3mm and the third, with the legal minimum of 1.6mm.

'What happens if you mix premium and budget tyres? And should you fit them to the front or rear?'

The test was to drive at speeds of 60, 70 and then 80km on a surface with 5 mm of water. At all three speeds, the newest tyre with the 8mm of thread showed no change on the wet surface and performed identical on both dry and wet conditions. At 3mm of thread the differences were noticeable and by the time the car had reached 80km, it was aquaplaning.

However nothing compared to the serious loss of control that occurs when driving the car with the 1.6mm thread. At a speed of 80km, the car had slid into the next lane before it was possible to regain full control of the car.

No matter how good your car is, the level of grip you have on the road is determined only by the quality of your tyres. When shopping for tyres, buy the very best you can afford. Think of them as insurance. Don't skimp.

Irish Independent

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