British Standard Puncture Repair
BS AU 159 Puncture
Repair Guide
TC Tyre & Autocare only carries out puncture repairs that fully comply with British Standard BS AU 159 — the industry gold standard for safe, permanent tyre repairs. Here's everything you need to know about when a tyre can and cannot be repaired.
The British Standard
What is BS AU 159?
BS AU 159 is the British Standard specification for repairs to tyres used on motor vehicles on the public highway. It defines exactly how a tyre can be safely and permanently repaired, which areas of the tyre are repairable, and which repair methods are acceptable. Any tyre repair that does not comply with BS AU 159 is considered unsafe and should not be used on UK roads.
Only Approved Method
The only BS AU 159-compliant repair for tubeless tyres is a combination mushroom plug and patch — applied from inside the tyre after removal from the wheel.
Full Speed & Load Rating
A tyre repaired to BS AU 159 standard can operate at its original speed and load rating — no restrictions apply after a proper repair.
Plug-Only = Unsafe
String plugs, external-only repairs, liquid sealants and temporary fixes are NOT recognised as acceptable under BS AU 159 and should be replaced with a proper repair.
Where Can a Tyre Be Repaired?
The Repairable Zone — Area T
Puncture repairs are only permitted in the central tread area of the tyre, known as Area T. This zone excludes the shoulder (where the tread curves towards the sidewall) and the sidewall itself. The width of Area T varies depending on the tyre's nominal section width.
Cross-section diagram — not to scale. Shaded areas indicate non-repairable zones.
Area T Dimensions by Tyre Width
The repairable zone (Area T) is defined as a percentage of the tyre's nominal section width. The maximum permitted penetration hole diameter is 6mm.
| Nominal Section Width | Area T (%) | Max Hole Diameter |
|---|---|---|
| Up to and including 155mm | 60% | 6mm |
| Over 155mm up to 200mm | 65% | 6mm |
| Over 200mm | 70% | 6mm |
Common Tyre Sizes — Area T Width
| Tyre Width | T (mm) | Tyre Width | T (mm) | Tyre Width | T (mm) |
|---|---|---|---|---|---|
| 125mm | 75 | 205mm | 144 | 285mm | 200 |
| 135mm | 81 | 215mm | 151 | 295mm | 207 |
| 145mm | 87 | 225mm | 158 | 305mm | 214 |
| 155mm | 93 | 235mm | 165 | 315mm | 221 |
| 165mm | 107 | 245mm | 172 | 325mm | 228 |
| 175mm | 114 | 255mm | 179 | 335mm | 235 |
| 185mm | 120 | 265mm | 186 | 345mm | 242 |
| 195mm | 127 | 275mm | 193 | - |
Source: BS AU 159g:2013 — Table F.1
Safety First
When a Tyre Cannot Be Repaired
Under BS AU 159, a tyre must not be repaired if any of the following conditions are present. In these cases, tyre replacement is the only safe option.
Sidewall or Shoulder Damage
Any damage outside Area T — including the shoulder (outer quarter of tread width) and sidewall — cannot be repaired as a minor repair. The tyre must be replaced.
Tread Depth Below 1.6mm
The legal minimum tread depth is 1.6mm. A tyre with inadequate tread depth cannot be repaired — it must be replaced regardless of the puncture location.
Puncture Larger Than 6mm
The maximum repairable penetration diameter is 6mm. Larger holes, cuts or tears cannot be safely repaired under BS AU 159.
Bead or Casing Damage
Damage to the bead (the part that seats on the wheel rim), casing break-up, or broken bead core means the tyre cannot be safely repaired.
Belt Separation
Radial ply tyres with belt separation (where the steel belts have separated from the casing) cannot be repaired and must be replaced.
Run-Flat Damage
Tyres that have been driven on while flat (under-inflation damage) may have internal structural damage that is not visible externally. These must be replaced.
Sidewall Rubber Separation
Tread or sidewall rubber separation indicates structural failure. Repair is not possible — replacement is required.
Exposed Cords
If steel cords are visible due to tread wear or sidewall scuffing, the tyre has reached the end of its serviceable life and must be replaced.
Previous Non-Standard Repairs
Tyres previously repaired with string plugs, liquid sealants, or other non-BS AU 159 methods must be assessed by a specialist before any further repair can be considered.
Unacceptable Repair Methods
The following methods are not recognised as acceptable under BS AU 159 and should not be relied upon as a permanent repair:
How We Do It
Our BS AU 159 Repair Process
Every puncture repair at TC Tyre follows the full BS AU 159 procedure. We use only combination mushroom plug-and-patch repairs — the only method that permanently seals both the inner liner and the penetration channel.
Initial Safety Inspection
The tyre is removed from the wheel and inspected internally and externally. We check tread depth, casing integrity, bead condition and liner. If any condition preventing repair is found, we advise on replacement.
Locate & Mark Damage
The puncture is located and the foreign object removed. The penetration is measured — repairs are only carried out if the hole is within Area T and does not exceed 6mm diameter.
Prepare the Penetration Channel
The channel is prepared from inside using a carbide mill cutter to create a clean, tapered hole that allows the repair plug to seat correctly.
Buff the Inner Liner
The inner liner is buffed to a suede finish around the repair area — approximately 5mm beyond the patch outline. This creates the surface for the adhesive to bond to.
Apply Vulcanising Solution
A specialist vulcanising accelerator is applied to the buffed area and penetration channel, then allowed to become tacky.
Insert Combination Patch & Plug
The combination mushroom repair unit is inserted through the channel from the inside. The plug fills the hole completely; the patch bonds to the inner liner.
Stitch & Seal
The patch is rolled with a corrugated stitcher from centre outwards to remove all air. The patch base and exposed buffed area are sealed with inner liner sealant.
Refit, Balance & Check
The tyre is remounted on the wheel, inflated to the correct pressure, rebalanced, and the repair is checked before the wheel is refitted to the vehicle.
Typical Repairable Puncture
A nail in the central tread area (Area T) — this is a repairable puncture under BS AU 159, provided the hole does not exceed 6mm and there is no internal damage.
BS-Approved Mushroom Patch Repair
A combination mushroom plug-and-patch repair as used by TC Tyre — the only BS AU 159-compliant method. The plug fills the channel; the patch seals the inner liner with vulcanising sealant.
TC Tyre's Commitment
We never use string plugs or external-only repairs. Every puncture repair at TC Tyre is carried out to the full BS AU 159 standard — tyre off the wheel, mushroom patch applied from the inside, rebalanced and checked before refitting.
Common Questions
Puncture Repair FAQs
How long does a puncture repair take?
Can I drive on a repaired tyre at full speed?
Is a string plug repair safe?
My tyre has a puncture near the edge of the tread — can it be repaired?
Can run-flat tyres be repaired?
How much does a puncture repair cost?
Get It Fixed Today
Book a Puncture Repair
Walk-ins are welcome — no appointment needed for most puncture repairs. Or use the form below to send us your details and we'll confirm availability.
Contact Us
Phone
01282 501162Mobile
07721 166844Address
Burnley, LancashireHours
Mon–Sat: 8:00am – 6:00pm
Walk-Ins Welcome
No appointment needed for puncture repairs. Simply turn up during opening hours and we'll get you sorted as quickly as possible — most repairs completed in 20–30 minutes.