A literature review about the road safety effects associated with tires, rims and wheels was carried out, where the literature search was done in consultation with the VTI Library and information centre. In conclusion; most research on this subject relates to tires, especially fatigue processes that lead to tread separation or tire explosion. Many studies have focused on the impact of under-inflation, while studies of over-inflation are less common. For heavy vehicles, overload is considered to be a probable factor behind premature tire aging and eventually failure. However, there are no studies that show how frequently vehicles operate with overloaded axles and the corresponding correlation between tire failures. Furthermore, there are only few studies concerning the occurrence of rim damage and its relationship to motor vehicle accidents. Regarding the wheel as a whole, almost all road safety related research is associated with wheel detachment. Nothing has been done concerning the influence of different wheel alignment, tire balancing, wheel hub centring etc. There are also no studies on the use of flat tire spray and the potential danger it can cause. Thus, several areas remain to be studied in further detail concerning the connection between tires, rims, wheels and road safety. For tires, a number of studies show how the tread depth affects the wet grip during braking, and how the tires with less than 3 mm tread depth lose about half of the available friction compared to new tires. Vehicles with worn tires (<3 mm) are also heavily overrepresented in Finnish accident statistics. No research was found on how different tire sizes and brands mounted on a vehicle affect its safety. Several studies show that there is a risk involved with mounting new tires on the front axle and worn tires on the rear axle. There is a consensus that during the replacement of two tires, the new tires should always be positioned on the rear axle, regardless if the vehicle is front or rear wheel driven. Among heavy vehicles, tire defects are second only to brake failure, as the most common vehicle defect among heavy trucks involved in fatal accidents in the U.S. For these accidents tire explosion represent 40 per cent of the reported tire failures. For heavy vehicles tread separation, followed by road hazard, is otherwise the most common reason for wheel failure. Tread separation and tire explosion are caused by tire fatigue, and for tire explosion the most common reason for fatigue is that the tires have been driven under-inflated or overloaded resulting in overheated tires. Another reason may be that the tire has aged, and that its cords have begun to oxidize. A wheel detached from the vehicle can be dangerous both for the vehicle and the environment. The latter is especially true when a wheel becomes detached from a heavy vehicle, and may collide with other road users and result in an accident. Wheel detachment during operation is a common problem in many countries for heavy vehicles and in for example the UK it is estimated that 3–7 fatalities occur each year as a result of this. The reason why the wheels come off heavy vehicles is incorrect installation. Incorrect tightening torque is the most common cause. Both too loose and too tight tightening torque may cause the wheels come off. (Author/publisher) This report may be accessed by Internet users at http://www.vti.se/en/publications/road-safety-effects-associated-with-t…
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