Wheel Modification Laws in the UK – Simple Guide

If you love customizing your ride, you probably have looked at wider rims, low‑profile tyres or even wheel spacers. But before you bolt anything on, you need to know the rules that keep you on the road legally. The UK has clear limits on wheel size, offset and fitment, plus a few steps you must follow to avoid MOT failures, insurance problems or costly fines.

Legal Limits on Wheel Size and Offset

First off, the law cares about tyre width and overall diameter. Your new tyre must stay within the original wheel arch without rubbing, and the overall diameter can’t differ by more than 3 % from the stock size. This rule protects the speedometer reading and ensures the braking system works as designed. For offset, the rule of thumb is to keep it within +/- 5 mm of the manufacturer’s spec. Going too far inward or outward can change the scrub radius and affect steering feel, which the DVSA checks during an MOT.

When you swap to a larger rim, make sure the tyre’s load rating matches or exceeds the original. Using a tyre with a lower load rating is a safety risk and an automatic MOT fail. If you’re unsure, check the tyre sidewall for the load index and compare it with your vehicle’s specifications, which you’ll find on the V5C registration document.

Wheel Spacers and Hub‑Centric Fitments

Wheel spacers are popular for wider stances, but they’re not a free‑for‑all. UK law requires that any spacer be hub‑centric, meaning it must line up perfectly with the hub bore. Non‑hub‑centric spacers can cause vibration, uneven tyre wear and even wheel detachment at high speeds. If you install spacers, you must also update the tyre size in your V5C if the overall track width changes beyond the allowed tolerance.

Most insurers treat spacers as a modification. Call your insurance provider before fitting them and note the change on your policy. Failure to do so can void coverage if an accident occurs. Some insurers even require a “Vehicle Modification Certificate” from a reputable installer, especially for spacers over 20 mm.

Finally, remember that any wheel change that alters the vehicle’s dimensions must be recorded on a V5C amendment (Section 6). You’ll need a MOT test after the amendment, and the examiner will check for proper fitment, clearance and secure mounting. The cost of a one‑off MOT test is minimal compared to a fine or insurance claim later.

Bottom line: stick to the original tyre diameter range, keep offset close to stock, use hub‑centric spacers, and tell both the DVSA and your insurer about the change. Follow these steps and you’ll enjoy a fresh look without worrying about legal trouble.