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Can You Change Your Tyre Size?

Thinking of changing your tyre size? Here’s everything you need to know before you do.

Yes — you can change your tyre size, but only within strict limits. Choosing tyres of the wrong size can affect your safety, performance, and even your insurance.

This guide explains what tyre size means, when a size change is possible, and how to ensure your choice complies with manufacturer and legal requirements.

🔍 What Is the Size of a Tyre?

When we talk about tyre size, we’re referring to several key dimensions and ratings that define how a tyre fits and performs. You’ll find these numbers and letters printed on the sidewall of your tyre.

Example: 205/55 R16 91V

Here’s what each element means:

• 205 – Width in millimetres

• 55 – Aspect ratio (height of sidewall as a percentage of width)

• R – Radial construction type

• 16 – Rim diameter in inches

• 91 – Load index (maximum weight per tyre)

• V – Speed rating (maximum speed at full load)

The correct size ensures that your tyres fit perfectly, perform safely, and deliver the comfort and efficiency your vehicle was designed for.

⚙️ What Size Changes Are Possible?

Every vehicle comes with a standard fitment and a few optional fitments — all officially approved by the manufacturer.

For example, the Peugeot 308 1.2 PureTech (2021) has several approved options:

• 195/65 R15 91H

• 205/55 R16 91V

• 205/50 R17 93V

• 225/45 R17 91V

• 225/40 R18 92V

This means the vehicle can be equipped with wheels ranging from 15 to 18 inches, as long as they are part of the manufacturer’s approved list.

Changing the diameter of the wheel often means replacing the rims as well — either with standard steel or lighter, more stylish aluminium versions.

✅ How to Check Approved Sizes

The list of tyre sizes approved for your vehicle is usually found:

• On a sticker inside the driver’s door

• In the owner’s manual

• Sometimes, inside the fuel filler flap

Only these manufacturer-approved sizes guarantee optimal safety and performance.

⚠️ Can You Fit a Non-Approved Size?

It’s strongly discouraged to fit tyres outside the approved size range.
In some countries, a small variation is tolerated — typically no more than -2% to +1.5% in overall diameter.

However, fitting non-approved tyres can cause:

• Safety risks (improper grip, braking imbalance, tyre deformation)

• Incorrect speedometer readings and odometer errors

• Vehicle inspection failure

• Fines or insurance complications in case of an accident

Always respect the manufacturer’s recommended dimensions to ensure your safety and compliance with regulations.

🚨 What Happens If You Ignore Size Approvals?

If your tyres do not match the approved specifications, you may face several consequences:

• ❌ Reduced safety — risk of blowouts or poor handling

• ⚠️ Fines during roadside inspections

• 🚫 Failed technical inspections (MOT / roadworthiness tests)

• 💸 Insurance invalidation in case of an accident

By staying within approved dimensions, you preserve performance, legal compliance, and peace of mind.

🌍 When Do You Need to Change Tyre Size?

If your vehicle is imported from another region, check that your tyres comply with local homologation standards (for example, European standards R30 and R117, marked with E2 on the sidewall).

Example:
If your car is imported into Europe from the United States, you may need to replace your tyres to meet European regulations and approval sizes.

❄️ Adjusting Load or Speed Ratings for Seasonal Tyres

For Winter Tyres

Winter or all-season tyres must carry the M+S (Mud & Snow) and 3PMSF (Three-Peak Mountain Snowflake) markings.

If your tyres are 3PMSF-certified, you can legally fit a lower speed rating than the manufacturer’s summer specification — as long as:

• A speed reminder label is placed inside the vehicle (visible to the driver).

If your tyres are only M+S (without 3PMSF), lowering the speed rating has been forbidden since January 2020.

For Summer Tyres

You can choose tyres with a higher load or speed rating, but never lower than the manufacturer’s recommendation.

🔁 How Many Tyres Should Be Changed at Once?

When changing tyre size, you must replace all four tyres at the same time.

Fitting different-sized tyres on the same vehicle (even just front or rear) can affect:

• Vehicle stability

• Braking performance

• Electronic systems such as ABS or traction control

Always resize all four tyres together for balanced performance and safety.

🧭 How to Find the Right Size for Your Vehicle

Now that you understand how tyre sizing works, the next step is to find the correct Michelin tyres for your car.

You can use Michelin’s online Tyre Selector Tool — simply enter your vehicle make, model, and engine type to find all manufacturer-approved sizes and tyre options.

✅ Key Takeaways

🟩 Drive Safely with the Right Tyre Size

Changing your tyre size can affect far more than appearance — it impacts your safety, vehicle handling, and legal compliance.

By always choosing manufacturer-approved sizes and fitting Michelin tyres, you ensure that every journey is both safe and efficient.