Fitting a wider set of alloy wheels, adding track spacers (spacers) or lowering the bodywork is the way to achieve an aggressive and clean flush fitment. Nevertheless, car enthusiasts regularly run into unpleasant surprises during the annual Algemene Periodieke Keuring (APK). The RDW (Rijksdienst voor het Wegverkeer) applies strict requirements in the official Regeling Voertuigen regarding wheel coverage, increases in track width and wheel arch clearance.

Frequently asked questions at our counter in Nijkerk include: "How many millimetres may a wheel or tyre protrude at most for the APK?", "What is the maximum 2% increase in track width and how do you calculate it?", "Is a tyre rubbing inside the wheel well an immediate reason for rejection?" and "Are tyre stretch and wobble bolts legal?" In this technical guide, the inspection and fitment specialists at Wheels 'N Customs set out all current RDW regulations clearly and transparently for you.

Article 5.2.48 of the Regeling Voertuigen sets out how wheels must be covered by the bodywork’s wheel arches. Among tuners there is often the misconception that wheels may never stick out beyond the wheel arch. In the Netherlands the legislation is more nuanced than in, for example, Belgium or Germany:

The track width is the distance between the exact centre of the left and right tread on the same axle. As soon as you fit wheels with a lower ET value or install track spacers (spacers), your car’s track width increases:

• The Statutory RDW Standard: The track width of passenger cars may increase by a maximum of 2.0% compared to the value officially registered on the registration certificate (or in the central RDW registration register).
• Why does this limit exist? Excessive track width increases the leverage on wheel bearings, wheel hubs and control arm bushes, which in cases of extreme widening can lead to metal fatigue and axle failure.
• What happens above 2%? Is the increase greater than 2%? Then the vehicle is not automatically illegal, but it must formally be presented at an RDW inspection station for an individual inspection with a strength certificate from the axle manufacturer.

During the APK the inspector lifts the vehicle to thoroughly inspect the suspension and steering. A strict safety requirement applies here:

Besides the wheel fitment, the inspector checks the tyres against the following legal criteria:

• Minimum Tread Depth (1.6 mm): The tyre must have at least 1.6 millimetres of tread in the main grooves around the entire circumference. Is the tread between 1.6 and 2.5 mm? Then the inspector issues a formal advisory note. (For winter tyres in Alpine countries, however, a minimum of 4.0 mm applies!).
• Carcass Break & Bulges (Tyre Hernia): A tear, lump or bulge on the tyre sidewall (caused by hitting a kerb hard) indicates an internally broken carcass. This is a life-threatening rejection point due to the acute risk of a blowout.
• Inner-Edge Wear Due to Negative Camber: On lowered cars that have not been aligned, the extreme inner edge of the tyre often wears through to the steel cords (the canvas), while the outer side still shows 5 mm of tread. As soon as the carcass fabric is visible, rejection is inevitable.
• Tyre Size per Axle: Tyres on the same axle must have the same size designation (e.g. both left and right 235/35 R19). A staggered set (different sizes between front and rear axle) is 100% permitted, provided the sizes per axle are identical.