Wheels
Wheels are chosen to fit the car: besides diameter and width, the bolt pattern (PCD), ET offset and centre bore must match. Below we explain what the rim markings mean and what Finnish rules require when you change wheels. Read the guide
Wheel dimensions
- Width and diameter – for example 7Jx17: the rim is 7 inches wide, J describes the flange shape and 17 is the diameter in inches. Tyre and rim sizes must be compatible.
- PCD (bolt pattern) – the number of bolts and the diameter of the circle they sit on, for example 5x112 (five bolts on a 112 mm circle).
- ET offset – the distance in millimetres from the rim's centreline to the face that mounts against the hub. A lower ET moves the wheel outwards, a higher one inwards.
- Centre bore – if it is larger than the hub, the wheel is centred with a hub-centric ring.
Also check that the seat of the wheel bolts or nuts (for example conical or ball) matches the wheel, and that the wheel's load rating is enough for the car's axle loads.
What Finnish rules allow
Under Traficom's regulation, the nominal rim diameter may be changed without a modification inspection by at most 26 mm – in practice one inch – from the size specified by the manufacturer or entered in the register. The tyre width may change by at most 40 mm or 20 % (whichever is greater) compared with the widest specified or registered width, provided the tyres' load capacity covers the car's technically permissible axle loads. In addition:
- the track width may change by no more than 30 mm, unless the car manufacturer states otherwise
- the tyres must not touch the car's structure in any steering or suspension position
- wheels with slotted bolt holes that fit several bolt patterns are not allowed, and only adapters intended by the car or wheel manufacturer may be fitted between hub and wheel
- if the outer diameter of the tyre changes, the speedometer reading must be corrected where necessary.
A bigger change requires a modification inspection.
Winter wheels
Keeping your winter tyres on their own wheels makes the seasonal change quicker. If the car has a direct tyre pressure monitoring system, the second set also needs sensors. Wash off road salt before putting the wheels into storage, tighten the wheel bolts or nuts to the torque the car manufacturer specifies and check them again after a short drive. If you are unsure whether a wheel fits, contact us.