MOT Tyre Failure: Tread Depth, Damage & Repair Costs 2025

Tyre-related defects are the second most common cause of MOT failures in the UK, accounting for 19.64% of all defects found during testing - only lighting faults are more common. In 2024, over 7 million vehicles had tyre issues identified during their MOT, with approximately 3.8 million failing purely due to tyre defects.

The frustrating part? Most tyre failures are completely preventable with a simple 5-minute check before your MOT. This comprehensive guide explains exactly what MOT testers check on tyres, the legal limits, common failure reasons, replacement costs, and how to check your tyres yourself to avoid MOT failure.

Quick Summary: Tyre Replacement Costs 2025

Most common tyre failure: Insufficient tread depth (below 1.6mm legal minimum)

Understanding MOT Tyre Testing

MOT testers perform comprehensive tyre checks on all four wheels (plus spare if fitted and intended for use):

What Gets Tested

1. Tread Depth Measurement

• Legal minimum: 1.6mm across central 3/4 of tread width
• Tested area: All the way around circumference
• Measured: Using official tread depth gauge
• Failure: Any point below 1.6mm = instant fail

2. Tread Condition

• Uneven wear patterns
• Cuts and lumps in tread
• Exposed cords or ply
• Damaged tread blocks

3. Sidewall Condition

• Cuts deeper than 25mm or 10% of section width
• Bulges or lumps (tyre wall separation)
• Exposed cords on sidewall
• Deep cracks or perishing
• Damage within 3cm of rim

4. Tyre Suitability

• Correct size for vehicle
• Speed rating adequate for vehicle
• Load rating sufficient
• Mismatched tyres on same axle
• Part-worn tyre markings (if applicable)

5. Tyre Age & Condition

• Excessive perishing/cracking
• Rubber degradation
• Age-related deterioration (10+ years typically)

6. Valve Condition

• Valve cap present (not always required but best practice)
• Valve sealing correctly
• No leaks
• Valve stem not damaged

Pass/Fail Criteria

Instant Failure if:

• Tread depth below 1.6mm anywhere
• Exposed cords or ply visible
• Bulge or lump in sidewall
• Cut deeper than 25mm or 10% width
• Mismatched tyres on same axle (different tread patterns/types)
• Tyre rubbing on any vehicle part
• Wrong size or speed rating for vehicle

Advisory if:

• Tread depth 2mm-3mm (legal but wearing)
• Minor perishing (not deep cracks)
• Uneven wear (may indicate alignment issue)
• Different brands on same axle (legal but not ideal)

Common Tyre Failures: Causes & Costs

1. Insufficient Tread Depth

Failure Rate: ~60% of all tyre-related MOT failures

Legal Requirements

UK Law: Minimum 1.6mm tread depth across:

• Central 3/4 of tread width
• Entire circumference of tyre

Why 1.6mm?

• Below this, water dispersion fails
• Aquaplaning risk increases dramatically
• Stopping distances increase by 50%+ in wet
• Grip in wet conditions severely reduced

Recommended Minimum

While 1.6mm is legal, safety experts recommend replacement at:

• Cars: 3mm minimum for safety
• 4x4/SUVs: 4mm minimum (heavier vehicles)
• Winter tyres: 4mm minimum (less effective below this)

Stopping distance impact (wet roads, 50mph):

• New tyres (8mm): 25 metres
• Legal minimum (1.6mm): 37 metres (+48%)
• Worn to 1mm (illegal): 43 metres (+72%)

How to Check Tread Depth

Method 1: 20p Coin Test (Quick Check)

1. Insert 20p coin into main tread grooves
2. Outer band of coin should NOT be visible
3. If outer band visible = below 1.6mm = FAIL
4. Check multiple points around tyre

Method 2: Tread Depth Gauge (Accurate)

1. Purchase gauge (£3-£10 from motor shops)
2. Insert into deepest part of tread groove
3. Read measurement on gauge
4. Check at least 4 points per tyre
5. Record lowest reading

Method 3: Tread Wear Indicators

• Small raised bars in tyre grooves
• Located at 1.6mm depth
• When tread wears level with bars = legal minimum reached
• Usually marked with "TWI" or triangle symbol on sidewall

Causes of Premature Tread Wear

• Underinflation (most common) - Causes edge wear
• Overinflation - Causes centre wear
• Misalignment - Causes inner/outer edge wear
• Driving style - Aggressive acceleration/braking
• Vehicle weight - Heavier vehicles wear faster
• Road conditions - Rough roads accelerate wear

Replacement Costs

Budget Tyres (£40-£80 per tyre):

• Brands: Sunny, Infinity, Landsail, Rapid
• Lifespan: 15,000-25,000 miles typically
• Best for: Low-mileage vehicles, city driving
• Pros: Cheapest option
• Cons: Shorter life, less grip in wet

Mid-Range Tyres (£60-£120 per tyre):

• Brands: Hankook, Kumho, Falken, Nexen, Toyo
• Lifespan: 25,000-40,000 miles
• Best for: Most drivers - best value
• Pros: Good performance, decent life
• Cons: Not premium brand cachet

Premium Tyres (£90-£200 per tyre):

• Brands: Michelin, Continental, Goodyear, Pirelli, Bridgestone
• Lifespan: 30,000-50,000+ miles
• Best for: Performance cars, high mileage, safety-conscious
• Pros: Best wet grip, longest life, quietest
• Cons: Most expensive initially

Cost Comparison Example (Medium car with 4 tyres):

• Budget tyres: £200-£320 total
• Mid-range tyres: £320-£480 total
• Premium tyres: £480-£800 total

Labour Costs Included:

• Fitting: £10-£20 per tyre
• Balancing: Included usually
• Valve replacement: £2-£5 per tyre
• Disposal: £2-£5 per old tyre
• Alignment check: £25-£50 (recommended)

Worth Upgrading Tyre Quality?

Premium tyres pay back if:

• Do high annual mileage (15,000+ miles)
• Drive in wet conditions frequently
• Value safety and grip
• Keep car long-term
• Can afford higher upfront cost

Budget tyres make sense if:

• Low annual mileage (under 8,000 miles)
• Mostly dry weather driving
• Car near end of useful life
• Tight budget constraints

Mid-range = Best value for most drivers

• 80% of premium performance at 60% of cost
• Decent lifespan
• Good safety ratings
• Reputable brands

2. Sidewall Damage

Failure Rate: ~15% of tyre-related MOT failures

What Causes Sidewall Damage

• Hitting kerbs (most common)
• Pothole impacts
• Underinflated tyres (increases flex)
• Manufacturing defects (rare)
• Age-related cracking

Types of Sidewall Failures

Bulges/Lumps:

• Caused by internal ply separation
• Air pressure pushes through weak spot
• Creates visible bulge on sidewall
• Very dangerous - can burst at any time
• Verdict: FAIL - Replace immediately

Deep Cuts:

• Deeper than 25mm or 10% of section width
• Caused by sharp objects, kerb damage
• May expose internal cords
• Verdict: FAIL if deep, advisory if superficial

Exposed Cords:

• Internal fabric showing through rubber
• Caused by severe wear or damage
• Very dangerous - structural failure imminent
• Verdict: FAIL - Replace immediately

Cracks/Perishing:

• Age-related rubber degradation
• UV damage from sunlight
• Appears as fine cracks in rubber
• Verdict: Advisory if superficial, FAIL if deep

MOT Failure Criteria for Sidewalls

Automatic fail if:

• Any bulge or lump present
• Cut deeper than 25mm
• Cut deeper than 10% of section width (whichever smaller)
• Exposed cords anywhere
• Deep cracks reaching internal structure
• Damage within 3cm of rim edge

Repair vs Replace

Cannot be repaired:

• Sidewall damage cannot be safely repaired
• Always requires tyre replacement
• No puncture repair on sidewalls

Costs:

• Single tyre: £40-£200 (as above)
• Must match tyre on same axle
• May need two tyres if partner too different

Prevention

• Maintain correct tyre pressures
• Avoid kerbs when parking
• Drive carefully over potholes
• Regular visual inspection
• Replace tyres over 10 years old

3. Mismatched Tyres on Same Axle

Failure Rate: ~8% of tyre-related failures

MOT Requirements

Same axle must have:

• Same tyre structure (radial or cross-ply)
• Same tread pattern type
• Similar tread depth (within reason)

Allowed to differ:

• Brand (can be different manufacturers)
• Age (can be different ages)
• Front axle different from rear axle

What Counts as Mismatched?

FAIL - These are NOT allowed on same axle:

• Radial tyre + cross-ply tyre
• Summer tyre + winter tyre
• Directional + non-directional
• Significantly different tread patterns
• Run-flat + standard tyre (on axle)

PASS - These ARE allowed on same axle:

• Different brands (e.g., Michelin + Continental)
• Different models from same brand
• Slight tread depth variation
• Different manufacturing dates

Why It Matters

Mismatched tyres cause:

• Uneven grip levels (handling imbalance)
• Different braking forces (pulls to one side)
• Unpredictable wet weather handling
• Potential stability control issues
• Insurance implications if crash occurs

Best Practice

Ideal setup:

• All 4 tyres same brand and model
• Front pair matched exactly
• Rear pair matched exactly
• Replace in axle pairs minimum

Acceptable setup:

• Front pair matched
• Rear pair matched
• Front different from rear (allowed)

Poor setup (but legal):

• Different brands on same axle
• Very different tread depths
• Increased safety risk

Replacement Strategy

If one tyre damaged:

• Check partner tyre tread depth
• If partner has 4mm+ tread left: Replace damaged tyre with matching type
• If partner has under 3mm: Replace both tyres on axle

If two tyres need replacing:

• Always replace axle pair together
• Use same brand and model
• Front-wheel drive: Replace front axle
• Rear-wheel drive: Replace rear axle
• All-wheel drive: Consider replacing all 4

Cost Implications:

• Single tyre: £40-£200
• Axle pair: £80-£400
• All four: £160-£800

4. Incorrect Tyre Size or Speed Rating

Failure Rate: ~5% of tyre-related failures

Tyre Size Requirements

Every vehicle has approved tyre sizes listed:

• In owner's manual
• On driver's door pillar sticker
• On fuel filler cap

Example tyre size: 205/55R16 91V

• 205 = Width in millimetres
• 55 = Aspect ratio (sidewall height)
• R = Radial construction
• 16 = Wheel diameter in inches
• 91 = Load index
• V = Speed rating

Common Size Errors

MOT failure if:

• Width too narrow (structural)
• Aspect ratio wrong (rubbing/incorrect load)
• Diameter wrong (incorrect rolling radius)
• Load index too low for vehicle weight
• Speed rating below vehicle capability

Examples:

• Fitting 195 width when 205 specified (might fail)
• Fitting 16" tyre on 17" wheel (dangerous, will fail)
• Load index 85 when 91 required (will fail)

Speed Rating Requirements

Common speed ratings:

• Q: 99mph (160km/h)
• S: 112mph (180km/h)
• T: 118mph (190km/h)
• H: 130mph (210km/h)
• V: 149mph (240km/h)
• W: 168mph (270km/h)
• Y: 186mph (300km/h)

MOT requirement:

• Speed rating must meet or exceed vehicle's maximum speed
• Cannot fit lower rated tyre than original specification
• Can fit higher rating (often done with winter tyres)

Example:

• Car specified with V-rated tyres (149mph)
• Fitting H-rated (130mph) = FAIL
• Fitting W-rated (168mph) = PASS

Load Index Requirements

Each tyre must support vehicle weight:

• Check vehicle weight plate
• Divide by 4 (or 2 for axle weight)
• Tyre load index must exceed this

Example:

• Vehicle kerb weight: 1,400kg
• Per tyre: 350kg minimum
• Load index 91 = 615kg capacity (OK)
• Load index 85 = 515kg capacity (OK but marginal)
• Load index 80 = 450kg capacity (might fail)

Costs of Wrong Size

If MOT fails for wrong tyres:

• Must replace with correct specification
• No choice of cheaper alternative
• Costs: £40-£200 per tyre as above
• Plus potential invalidated insurance

5. Tyre Age and Perishing

Failure Rate: ~4% of tyre-related failures

How Old is Too Old?

Tyre age recommendations:

• 0-6 years: Generally fine if stored correctly
• 6-10 years: Inspect carefully for perishing
• 10+ years: Replace regardless of tread depth
• Storage: Unused tyres also age and degrade

Finding Tyre Age

Every tyre has DOT code on sidewall:

Example: DOT AB12 CDEF 3219

• Last 4 digits = Manufacturing date
• "3219" = Week 32 of 2019
• This tyre made in August 2019

Reading the code:

• First 2 digits = Week number (01-52)
• Last 2 digits = Year (19 = 2019)
• Always on outer sidewall

Why Tyres Age

• Rubber compounds degrade over time
• UV exposure (sunlight damage)
• Ozone in atmosphere
• Temperature cycles
• Chemical breakdown
• Occurs even if not used

Signs of Age-Related Failure

Perishing (Dry Rot):

• Fine cracks in sidewall
• Spider-web pattern
• May appear in tread grooves
• Rubber feels hard/brittle

Severity Levels:

• Hairline surface cracks = Advisory
• Deep cracks = Major defect
• Cracks reaching inner structure = Dangerous defect

Colour Changes:

• Greyish discolouration
• Rubber looks faded
• Loss of sheen
• Indicates UV degradation

MOT Standards for Age

Will fail if:

• Deep perishing/cracking visible
• Cracks penetrate to inner structure
• Rubber so degraded it's unsafe
• 10+ years AND showing deterioration

May pass with advisory if:

• Light surface perishing only
• No structural damage
• Under 10 years old
• Otherwise safe condition

Replacement Costs

Same as tread depth failures:

• Budget: £40-£80 per tyre
• Mid-range: £60-£120 per tyre
• Premium: £90-£200 per tyre

Prevention

• Park in shade when possible
• Use tyre dressing sparingly (can accelerate cracking)
• Maintain correct pressures (reduces flex)
• Regular driving (static storage worse)
• Replace 10-year-old tyres regardless

6. Part-Worn Tyres and MOT

Failure Rate: Variable - depends on condition

Legal Requirements for Part-Worn Sales

Part-worn tyres must be marked:

• "PART WORN" in letters 4mm+ high
• Seller's name and address
• No dangerous repairs present
• Minimum 2mm tread depth

MOT Treatment

Part-worn tyres tested same as new:

• Same 1.6mm minimum tread
• Same sidewall damage rules
• Same matching requirements
• Legal marking not checked in MOT (sales requirement only)

Risks of Part-Worn Tyres

Common issues:

• Unknown history (could have crash damage)
• Internal damage not visible
• May have illegal repairs
• Often only 3mm tread (limited life)
• Age often unknown
• Could fail next MOT soon

Costs vs new:

• Part-worn: £15-£40 per tyre
• Budget new: £40-£80 per tyre
• Extra £25-£40 gets 8mm tread vs 3mm

Recommendation

Avoid part-worn tyres if possible:

• Minimal savings vs budget new
• Unknown safety history
• Short remaining life
• Better value buying budget new

If buying part-worn:

• Check DOT date code (reject if 6+ years)
• Inspect for repairs (reject if sidewall repaired)
• Measure tread (minimum 4mm to be worthwhile)
• Check for bulges/damage
• Get receipt with seller details

DIY Tyre Checks Before MOT

Complete check takes 10 minutes:

1. Tread Depth Check (5 minutes)

For each tyre:

1. Insert 20p coin into main grooves
2. Check at least 4 points around circumference
3. Outer band visible = too worn
4. Repeat in each tyre groove
5. Record any tyres below 3mm

Tools needed:

• 20p coin (free)
• Or tread gauge (£3-£10)

2. Visual Inspection (3 minutes)

Check each tyre for:

• Bulges or lumps on sidewall
• Cuts or cracks in sidewall
• Uneven wear (indicates alignment issue)
• Objects embedded in tread
• Exposed cords anywhere
• Perishing or cracking

Look specifically:

• Inside edge (often worn first)
• Sidewall near rim (damage zone)
• Tread shoulders (edge wear)

3. Tread Pattern Match (1 minute)

Check each axle:

• Front left vs front right - same pattern?
• Rear left vs rear right - same pattern?
• Front can differ from rear

4. Tyre Age Check (1 minute)

Read DOT code:

• Find 4-digit date code on sidewall
• Calculate age from manufacture date
• Plan replacement if 8+ years old

Red Flags to Address Before MOT

Replace immediately if:

• ❌ Tread below 2mm (will fail soon if not now)
• ❌ Any bulge or lump visible
• ❌ Cuts deeper than 25mm
• ❌ Exposed cords showing
• ❌ Mismatched tyres on same axle

Monitor closely if:

• ⚠️ Tread 2-3mm (legal but wearing)
• ⚠️ Light perishing visible
• ⚠️ Tyre over 8 years old
• ⚠️ Uneven wear pattern

Cost-Saving Strategies

1. Replace Before MOT

Proactive replacement saves money:

• Identify worn tyres 1-2 weeks before MOT
• Shop around for best tyre prices
• Avoid MOT failure fee (£54.85)
• Time to find deals/offers

Typical saving: £30-£80 (avoiding retest, finding better prices)

2. Buy Tyres Online

Online retailers often cheaper:

• Blackcircles.com
• MyTyres.co.uk
• Kwik Fit website
• Saving: 10-30% vs in-store

Process:

• Buy online
• Book fitting at local garage
• Garage fits tyres you purchased
• Still get warranty

3. Compare Tyre Prices

Price varies enormously for same tyre:

• Get quotes from 3+ retailers
• Check online vs in-store
• Look for fitting deals
• Ask about price matching

Example (205/55R16 Michelin):

• Expensive: £140 fitted
• Average: £95 fitted
• Cheap: £75 fitted (online)
• Saving: £65 per tyre!

4. Replace in Pairs

When one tyre damaged:

• If partner has 4mm+ tread: Replace one
• If partner under 3mm: Replace pair
• Saves replacing pair twice

5. Timing Your Purchase

Best times for tyre deals:

• January sales (winter clearance)
• Summer (7-8 month MOT boom)
• Black Friday (November)
• End of month (sales targets)

Worst times:

• March MOT rush
• September MOT rush
• December (winter demand)

6. Maintenance to Extend Life

Free actions that add life:

• Check pressures monthly (prevent edge wear)
• Rotate tyres every 6,000 miles (even wear)
• Avoid aggressive driving (reduces wear)
• Gentle kerb approaches (prevent damage)
• Remove debris from tread (prevent punctures)

Paid maintenance worth doing:

• Wheel alignment check annually (£25-£50)
• Wheel balancing when fitting (usually included)
• Valve replacement when fitting new tyres (£2-£5)

Potential savings: 5,000-10,000 extra miles per set = £50-£150 value

When to Replace vs Wait

Replace Before MOT If:

✅ Tread at or below 2mm (close to limit) ✅ Any tyre over 8 years old ✅ Visible damage (bulges, deep cuts) ✅ Mismatched on same axle ✅ Very uneven wear

Can Wait Until After MOT If:

⏸️ Tread 3mm+ (still legal with margin) ✅ No damage visible ✅ Matched on same axle ✅ Under 6 years old ✅ Even wear pattern

Decision Framework

Calculate cost to wait:

• MOT failure if tyres fail: £54.85 retest
• Plus tyre costs: £40-£200 per tyre
• Inconvenience: Time off work, multiple visits

vs cost to replace now:

• Tyre costs: £40-£200 per tyre
• Peace of mind: MOT pass guaranteed
• Time to shop: Find best deals

Verdict: If any doubt, replace before MOT.

Frequently Asked Questions

What is the legal minimum tread depth?

1.6mm across the central 3/4 of the tread width, around the entire circumference. However, safety experts recommend replacing at 3mm for cars and 4mm for SUVs/4x4s, as grip reduces significantly below these levels.

Can I pass MOT with different tyres on front and rear?

Yes. Different tyres front vs rear is perfectly legal and won't fail MOT. However, tyres on the same axle must be similar (same structure and tread pattern type). You cannot have mismatched tyres left-to-right on either axle.

How do I check my tyre tread depth?

20p coin method: Insert a 20p coin into the main tread grooves. If the outer band of the coin is visible, your tread is below the 1.6mm legal minimum.

Tread depth gauge: Purchase a gauge (£3-£10) and insert into the deepest part of the tread groove. Check multiple points around the tyre.

Can I repair a tyre with sidewall damage?

No. Sidewall damage cannot be safely repaired. Any bulge, deep cut, or exposed cords on the sidewall requires complete tyre replacement. Only punctures in the central tread area can sometimes be repaired.

Do all 4 tyres need to be the same brand?

No. Different brands are allowed, even on the same axle. However, tyres on the same axle must have:

• Same structure (radial or cross-ply)
• Similar tread pattern types
• Comparable tread depths

Best practice is to match tyres in axle pairs (front pair matched, rear pair matched).

How old is too old for tyres?

10 years maximum, regardless of tread depth or condition. Tyres degrade over time due to UV exposure, ozone, and chemical breakdown. Check the DOT code on your sidewall - the last 4 digits show week and year of manufacture (e.g., "3219" = week 32 of 2019).

Will slightly different tread depths fail MOT on same axle?

No. Different tread depths on the same axle won't fail MOT, provided:

• Both tyres are above 1.6mm minimum
• Tread patterns are similar type
• Tyres are same structure (radial)

However, very different depths (e.g., 7mm vs 2mm) create handling imbalance and should be avoided.

Can I mix winter and summer tyres?

Not on the same axle. You cannot have a winter tyre on one side and summer tyre on the other side of the same axle - this will fail MOT. You can have winter tyres on one axle and summer on the other (though not recommended for handling).

Are budget tyres safe for MOT?

Yes, if they meet legal requirements. Budget tyres must have:

• Minimum 1.6mm tread depth
• Correct size and load rating
• No damage or defects
• Proper safety markings (E-mark)

Budget tyres pass MOT if in good condition, though premium tyres offer better wet grip and longer life.

What if I can only afford to replace one tyre?

If budget constrained:

1. Replace the worst tyre first (safety priority)
2. Ensure it matches its partner on same axle
3. Plan to replace partner tyre within 6 months
4. Consider budget tyres (£40-£80 per tyre)
5. Check for online deals or payment plans

Never drive on illegal tyres - the fine is £2,500 per tyre plus 3 penalty points.

Can I fit run-flat tyres to replace standard tyres?

Generally no on the same axle as standard tyres (will fail MOT). Run-flats and standard tyres have different handling characteristics. If your vehicle came with run-flats, you should replace with run-flats. If it came with standard, you can replace all 4 with run-flats but not mix on same axle.

Will uneven tyre wear fail MOT?

Not automatically. Uneven wear (inside/outside edge wear) will fail MOT if:

• Any area is below 1.6mm minimum
• Wear exposes internal cords
• Structural damage present

Uneven wear will likely get an advisory noting potential alignment issues. Address alignment (£25-£50) to prevent replacing tyres prematurely.

How long do tyres typically last?

Depends on many factors:

• Budget tyres: 15,000-25,000 miles
• Mid-range tyres: 25,000-40,000 miles
• Premium tyres: 30,000-50,000 miles

Factors affecting lifespan:

• Driving style (aggressive = shorter life)
• Vehicle weight (heavier = more wear)
• Road conditions (rough = faster wear)
• Tyre pressure (incorrect = uneven wear)
• Wheel alignment (poor = edge wear)

Conclusion: Making Smart Tyre Decisions

Tyre failures cause nearly 20% of all MOT failures, yet they're one of the easiest defects to prevent with regular checks.

Key takeaways:

1. Check monthly: 5-minute tread depth and visual inspection
2. Replace at 3mm: Don't wait for legal minimum (1.6mm)
3. Buy in pairs: Replace axle sets for safety and value
4. Shop around: Tyre prices vary 50%+ for identical product
5. Pre-MOT check: Identify worn tyres 2 weeks before test
6. Age matters: Replace tyres over 10 years old regardless of tread
7. Match axles: Never mix tyre types on same axle
8. Maintain pressure: Monthly checks prevent premature wear

Cost-conscious strategy:

• Budget tyres: £40-£80 per tyre (adequate for low mileage)
• Mid-range tyres: £60-£120 per tyre (best value for most)
• Premium tyres: £90-£200 per tyre (high mileage/safety)

Before your next MOT:

1. Check all tyres with 20p coin test
2. Inspect sidewalls for damage
3. Verify matching on each axle
4. Replace any below 3mm tread
5. Budget £80-£400 for axle pair if needed

Check your MOT history now to see previous tyre advisories and predict when replacement is needed.