An Important Tip For Four Wheel Drive Owners
AN IMPORTANT TIP FOR FOUR WHEEL DRIVE OWNERS
If you have a four wheel drive, care must be taken in accurately matching the tyres to avoid potential damage to the transmission system.
"Different brands of light truck tyres with the same size marking on the sidewalls may have a difference of two or three centimetres in outer diameter which translates into a significant difference in rolling circumference," Bill Prebble, product development manager for Dunlop and Goodyear Tyres said. "There is even a significant difference between the rolling circumference of a worn and new tyre of the same brand.
"The effect of the difference in diameter is that if the two tyres are on the same drive line, i.e. front or rear, then they wind up the differentials. Similarly if the tyres are mismatched front to rear.
"We had an inquiry from a customer recently who had a quite new four wheel drive that had three tyres of one type and the fourth of another on the vehicle. The tension that built up in the transmission meant he could not move the range lever out of four wheel drive unless he reversed or jacked the vehicle up to remove the tension.
"Fortunately he was able to identify the problem and replaced the odd tyre with the spare which was a match. Often our retail stores find similar mismatches that create unnecessary wear on transmission components.
"There are no industry standards around the world that that set maximum diameter tolerances between tyres on four wheel drives. It is up to vehicle owners to be aware of the potential problems tyre mismatching can cause.
"Most problems we see are with four wheel drive vehicles, but with the number of four wheel drive sedans now on the road, owners of these vehicles must also be aware of the need to fit matched tyres," he said.