"Tyre slightly damaged/cracking or perishing": what it means
"Tyre slightly damaged/cracking or perishing" means the tester saw cracks in the rubber or minor damage, usually on the sidewall, but nothing that reaches the tyre's internal structure. Fine surface cracks are normal on older tyres. Deep cracks, cuts or any bulge are not. Have a close look yourself, check the tyre's age, and replace it sooner rather than later if the cracks are more than skin-deep.
Why tyres crack
Tyre rubber contains chemicals that keep it supple. Over time sunlight, ozone in the air, heat and simply sitting still break them down, and the surface starts to craze. You'll often see it:
- on the sidewall, near where it meets the tread
- between the tread blocks
- on cars that sit for long periods, such as caravans, weekend cars and anything stored outside
- on tyres that have been run under-inflated, which makes the sidewalls flex more
Some tyre shine products can speed it up too.
Harmless cracks vs dangerous ones
Squeeze the sidewall gently between your fingers and watch what the cracks do.
| What you see | What it means |
|---|---|
| Fine lines on the surface that close up when you let go | Normal ageing. Keep an eye on it |
| Cracks that open into clear gaps when you flex the rubber | Getting deep. Plan to replace the tyre |
| Cracks deep enough to see anything underneath, or fabric or cords showing | Replace it now. Exposed cords are an MOT fail |
| A bulge or lump on the sidewall | The internal structure has failed. Dangerous, replace it before driving further |
The MOT treats a lump, bulge or tear caused by the tyre's structure separating as a dangerous defect. A cut deep enough to reach the ply or cords is a major fail. Bulges usually come from hitting a kerb or pothole, and they can blow out without warning.
How old is your tyre?
Every tyre has a four-digit date code on the sidewall, usually after the letters DOT inside an oval. The first two digits are the week and the last two are the year. So 2319 means week 23 of 2019.
There's no legal age limit for car tyres in the UK. Many tyre makers advise replacing them at ten years old whatever the tread depth, and having them checked regularly from around five years. If your tyre is cracking and it's that kind of age, that's your answer.
It's worth checking the spare too. A spare that's never been used can be fifteen years old and badly perished, and it's the tyre you'll be relying on at the side of a motorway. Testers often mention defects on the spare as advice, even though it isn't part of the pass or fail.
What it costs
The cost is the same as any tyre replacement. A typical family-car tyre fitted costs roughly £60 to £160 depending on size and brand. If only one tyre on an axle is cracked but the other has similar wear and age, it's worth replacing both so grip is even side to side.
What to do now
- Look at every tyre, including the inner sidewall and the spare.
- Read the date code.
- If the cracks open up when flexed, or the tyre is old, get a price for replacements.
- Check tyre pressures every couple of weeks in the meantime. Under-inflation makes cracking worse.
If your MOT also flagged tread depth, read what "worn close to legal limit" means. To sort the rest of your advisories by urgency, use the MOT advisory decoder.
Got more than one advisory?
Paste your whole MOT result into the decoder. It explains every line, sorts them by urgency and adds up a rough repair budget.
Decode my MOT