CU30 — Using a Vehicle with a Defective Tyre

Points can apply per tyre, not per stop — four bald tyres is a bigger problem than most drivers realise.

CU30 covers using a vehicle with a tyre that's defective — worn below the 1.6mm legal minimum tread depth across the central three-quarters of the tyre's width, cut, bulging, or otherwise unfit for the road. It's usually spotted at a routine stop or roadside check rather than by camera.

The standard fixed penalty is £100 and 3 points, but critically that's per tyre: a car stopped with two defective tyres can face 6 points and two separate fines in one encounter, and four defective tyres put a driver straight into totting-up territory. Whether all the tyres cited were genuinely below the legal limit, and measured correctly, is worth checking before accepting multiple endorsements at once.

What CU30 penalties look like

  1. Legal minimum tread depth: 1.6mm across the central three-quarters of the tyre, around the full circumference.
  2. Fixed penalty: £100 and up to 3 points — per defective tyre, not per stop.
  3. Four defective tyres in one stop can mean up to 12 points in a single encounter.
  4. Cuts, bulges and structural damage count as defects even with adequate tread.
  5. Points stay on the driving licence for 4 years.

Can I really get points for each tyre separately?

Yes — the offence is assessed per tyre, so multiple defective tyres found at the same stop can each carry their own points and fine. That's exactly why it's worth checking every measurement was taken correctly rather than accepting the total as given.

My tyre was just under the limit — is there any leeway?

The legal limit is 1.6mm and enforcement is generally strict at or below it, but how and where the measurement was taken matters — tread depth varies across a tyre's width, and correct measurement points to the specification. That detail is worth having reviewed.

Does a CU30 affect my insurance?

Yes, as a licence endorsement it's disclosable to insurers for the usual period and can affect premiums, particularly where multiple tyres were involved in one stop.

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