New wheels: Know what's crucial and right
BACK TO OVERVIEWNew rims and tyres not only enhance a car's appearance but also affect its technical characteristics, including traction, rolling circumference, track width, and ground clearance, which in turn can positively or negatively impact the car's handling. It is therefore important to understand these relationships to ensure both operational safety and legal compliance.
Key terms
The rolling circumference is the distance a wheel covers in one revolution without slip.
This value affects the speedometer reading. A change in rolling circumference can lead to discrepancies between the displayed and actual speed and can impact electronic assistance systems
The offset, measured in millimetres, is the distance between the centre of the wheel and the wheel mounting surface.
A change in offset affects the vehicle’s track width. For example, an offset of 30 mm and a new rim with 20 mm offset result in an increase in track width by 20 mm per axle.
The bolt pattern indicates the number and spacing of the wheel bolt holes. For example, 5x112 means five holes on a circle with a 112-mm diameter.
The tyre size is composed of width, height, and rim diameter. For example, “245/40 R20” means 245 mm width, height 40% of the width, and a 20-inch rim diameter.
The alignment is the positioning of the wheels relative to each other. Incorrect alignment can lead to uneven tyre wear and poor cornering performance. The track width is the distance between the contact points of the wheels on one axle.
Useful requirement
Since November 2014, a Tyre Pressure Monitoring System (TPMS) has been mandatory in new cars. It monitors tyre pressure and increases driving safety. There are indirect systems that use existing sensors and direct systems with additional pressure sensors. DOTZ relies on its own TPMS sensors, which are displayed in the
online configurator when the relevant car requires them. TPMS is extremely useful and enhances driving safety by alerting the driver to deviations from a pre-set target pressure. Since incorrect tyre pressure can also lead to higher fuel consumption, TPMS helps with saving costs as well.
What needs to be registered?
Many vehicle modifications need to be registered. Among the few modifications that don’t require registration are window tinting films and exhaust systems approved with an E number (depending on the country, these laws may vary). When it comes to wheels, only standard rims and tyres do not need to be approved. All other wheels require registration, even if they are the same size as the standard rims.
Exceptions are wheels with ECE Regulation 124, as they are exempt from registration, although the relevant documents must always be carried. The effort to certify wheels according to ECE 124 is very high, which is why such wheels are rare. Large manufacturers like DOTZ make an exception as they have some of these in their range, which can be specifically filtered through the online configurator.