A tyre cracking or perishing advisory means the rubber is ageing but no cords or structure are exposed. The DVSA manual fails a tyre only when a cut reaches the ply or cords (major) or the structure fails with a bulge or tear (dangerous).
Checked 23 October 2026 against the DVSA MOT inspection manual
- Separate cracking defect: None in the manual
- Cut reaching cords: Major defect
- Bulge or tear: Dangerous defect
- DVSA manual: 5.2.3
What this advisory means
An advisory is recorded when an item is not deteriorated enough to justify a fail, and it exists to inform the presenter. Advisories do not cause a fail and are recorded in the MOT history.
The DVSA manual has no separate defect for cracking or perishing. It is judged under the cut and structure rules: if cords are reached it is a major defect, and structural failure is dangerous. Where the damage falls short of those thresholds, the tyre does not meet the criteria for a fail.
Testers who are unsure pass the tyre and give an advisory. This reflects the absence of a dedicated defect and the judgement required under the cut and structure rules. The advisory records the observed condition without changing the test result.
When it becomes an MOT fail
The DVSA manual contains no separate defect entry for tyre cracking or perishing. Such deterioration is assessed under the cut and structure rules instead. Where cracking has progressed so that the cords are reached, the tyre is recorded as a major defect. Where the condition amounts to structural failure, it is recorded as dangerous. A tester who is unsure whether the damage meets either threshold passes the tyre and issues an advisory, so the advisory itself is not a defect category.
A cut deep enough to reach the ply or cords is a major defect under 5.2.3 d i. A lump, bulge or tear resulting from structural failure, including exposed or damaged cords, is a dangerous defect under 5.2.3 d ii. A cut exceeding 25mm or 10% of the section width, where cords can be felt, is also a fail. These are the specific conditions that move cracking or perishing from an advisory into a major or dangerous defect.
The distinction rests on what the damage exposes or causes, not on the visible surface pattern of cracks. Cracking that remains within the rubber and does not reach the cords stays outside the fail criteria and attracts an advisory where noted. Once cords are reached, or the casing shows structural failure through a bulge, lump or tear, the manual references above apply and the outcome is a major or dangerous defect rather than an advisory.
| DVSA manual ref | Defect | Result |
|---|---|---|
| 5.2.3 (d)(i) | Cut deep enough to reach the ply or cords | Major |
| 5.2.3 (d)(ii) | Lump, bulge or tear from structural failure | Dangerous |
Source: DVSA manual section 5: tyres, checked 23 October 2026.
Frequently asked questions
What is an MOT advisory?
An advisory is used when an item is not deteriorated enough to justify a fail, to inform the presenter. Advisories do not cause a fail and are recorded in the MOT history.
Is tyre cracking or perishing a separate MOT defect?
The DVSA manual has no separate defect for cracking or perishing. It is judged under the cut and structure rules: if cords are reached it is a major defect, and structural failure is dangerous.
Why would a tester give an advisory rather than a fail for cracked tyres?
Testers who are unsure pass the tyre and give an advisory. This records the concern in the MOT history without failing the vehicle, because the cracking has not reached the threshold for a defect.
When does a cut in a tyre become a major defect?
A cut deep enough to reach the ply or cords is a major defect (5.2.3 d i). A cut over 25mm or 10% of the section width where cords can be felt is a fail.
What tyre damage is classed as dangerous?
A lump, bulge or tear from structural failure, including exposed or damaged cords, is a dangerous defect (5.2.3 d ii). This is the most serious category and the vehicle must not be driven.
