Why do wheel nuts have to be retightened after a wheel change?
Why do wheel nuts need to be tightened?
The recommendation to retighten the wheel nuts after 50 to 100 km, but at the latest after 200 km, is a simple precautionary measure. During the first kilometers after a wheel change, the nuts may loosen slightly. The purpose of retightening is to prevent wheel bolts or nuts from completely loosening and a wheel eventually coming off.
In principle, nothing, if the wheel nuts have been tightened to the correct torque after a wheel change at a specialist workshop. However, experienced fitters sometimes make mistakes and do not tighten the nuts to the correct torque. Also, on a used vehicle and wheels, not all parts fit perfectly as they did when new.
If the contact surface between the wheel and the hub has not been cleaned before fitting, the wheel may not seat evenly. The rim may then move slightly when driving under certain loads. The stress on some wheel nuts then decreases, allowing them to loosen. This game increases with each kilometer traveled. Once a lug nut is loosened, it can continue to unscrew quite quickly from vibration and even fall off. It is rare for a wheel to come off the vehicle while driving. However, it is still possible.
What are the signs of loose wheel nuts?
Every motorist is familiar with the noises and behavior of his car on the road. This is why unusual noises and vibrations are usually noticed very quickly. When the wheel nuts loosen, vibrations and knocking and knocking noises occur. These vary with speed. If you notice unusual vibrations or noises after a wheel change, return to the garage as soon as possible and have the wheels checked. When the car is on its wheels, it is hardly possible to see for yourself whether the wheel nuts are loose.
What tool to use to tighten the nuts?
In principle, your on-board tools are sufficient to tighten the wheel nuts. You will usually find the wheel wrench with the jack near the spare tire or in a compartment in the trunk of your car. You can also use a wheel cross. These two tools , however, are not optimal for tightening wheel nuts. These tools do not make it possible to respect the prescribed tightening torque. If you are using a wheel wrench or wheel cross , chances are you are overtightening the nuts. It is best to use a torque wrench. You will find torque wrenches from 20-30 euros in all DIY stores. This investment is definitely worth it.
What torque should wheel nuts be tightened to?
The prescribed torque for retightening wheel nuts varies from vehicle to vehicle. There are big differences between city cars and SUVs or heavy minivans. For city cars and compact sedans, the prescribed torque for retightening the wheel nuts is approximately 80-110 newton meters. For touring cars and limousines, the torque is already significantly higher, at around 130 to 160 Nm. Wheel bolts for heavy-duty vehicles should be tightened to 200 Nm. For the exact prescribed torque for your car’s wheels, see your vehicle manual.
How to tighten the nuts?
To tighten the lug nuts, park your vehicle on a level surface. Apply the handbrake and engage first gear or put the automatic transmission in park. You can then retighten the nuts on each wheel one at a time. In doing so, you must observe a certain order.
To ensure long-lasting, safe and solid wheel fixing, you must tighten the wheel nuts in a specific order. This varies depending on whether your wheels are equipped with 4 or 5 hole rims . For 4-hole rims, tightening is done crosswise. This means you tighten the top left nut/bolt first. Then you tighten the bottom right nut, then the bottom left nut and finally the top right nut.
For a 5-hole rim, tighten the star nuts. Start at the top middle, then retighten the bottom left lug nut and then the top right lug nut. Then the top left lug nut and finally the bottom right lug nut. This order ensures uniform support over the entire surface of the rim.
Who is responsible for an accident caused by loose wheel nuts?
If you change the wheels of your car yourself, you are of course responsible if the wheel nuts loosen and an accident occurs. If you change the wheels in a specialist garage, the legal situation also seems clear.
Garages tell their customers that wheel nuts should be retightened after a certain distance has been driven. We can then think that motorists are thus responsible for it. However, according to a recent judgment of the Munich Court of Appeal of May 19, 2021, the responsibility of the garage for the correct execution of the wheel change cannot be passed on to the customer.
The judgment was issued following a complaint from a Mercedes driver . The left rear wheel of his vehicle had come off on the highway after a wheel change. An accident ensued with serious material damage. The driver of the Mercedes then claimed damages from the garage. He considered that the wheel change had not been carried out correctly. In a first instance judgment, the driver was found to be co-responsible.