Driving tip
Number 9
Friday 29 February 2008
Although most tyres are made to very high quality standards, there are still variations in the thickness of the rubber, the steel belts and the radial webbing that form the structure. One consequence of the variations is a slight weight difference around the tyre. This is well known and easily cured by balancing the wheel and tyre.
A less well known effect of the variability is something called run-out – a measure of how straight the tyre will run if fitted to a wheel and allowed to roll along a flat level surface. Some will run straight and true, others will veer to the left or right in varying degrees. You will see an indication of this on most new tyres – have you ever noticed coloured lines running around the tread on your new tyre? Some of these are to give the tyre distributors easy to read information about where the tyre should be shipped to, but one of them will be a run-out indicator – usually red or blue, and the extreme left or right hand line. The nearer to the centre it is, the straighter the tyre will run, and which side of the centre it is denotes the direction of the run-out.
A steering problem can arise if both tyres on the front axle happen to run out significantly in the same direction. Ideally, when you’re next buying new tyres you should select two with run-out of about the same amount, but in opposite directions – in other words, with the coloured lines both to the inside of the centre of the tyre, or both to the outside. That way the two will cancel each other out and you’ll get straight steering.
Regardless of the tyre combination, a regular weekly check of the tyre pressure – when they are cold – is the best way to avoid premature wear.You will feel the improvement in the fuel consumption as well.And a quick check for condition (no cuts, bulges, or screws sticking out of the rubber!) at the same time is good practice, too.
ENDS
342 words
NOTES TO EDITORS
1. Issued by the IAM Press Office, telephone 020 8996 9600. We have an ISDN line for interviews.
2. The IAM (Institute of Advanced Motorists) directly influences the driving and riding of more than 160,000 road users a year (full members, associates and commercial clients) in the UK and Ireland. Established in 1956, the IAM is today best known for the advanced driving test and the advanced driving course. The IAM has grown to become the UK’s leading road safety charity, dedicated to raising driving standards, engaging with the road-using public and influencing road safety policy. IAM Fleet, the corporate arm of the IAM, has two subsidiary companies, Drive & Survive and Fleet Ireland. It also operates IAM Pro-Drive.
3. A 2006 report by Brunel University, following an 18 month study, concluded that “advanced driver training produces safer drivers and lower accident involvement”, with measurable improvements in knowledge, skills and attitude. The “Driving Tips” provided by the IAM are part of our broader road safety mission and not intended as a substitute for the advanced driving course.
4. In January 2007, the IAM Motoring Trust was established as the research and advocacy arm of the IAM. The IAM Motoring Trust will undertake research, promote practical policies, act as an advocate for safer roads, safer drivers and safer vehicles and encourage responsible motoring through education and training
