The Ins & Outs of Tyre Pressure

Getting your car tyre pressure right might seem like a small detail, but it makes a big difference to your safety, fuel economy, and how long your tyres last. Let’s break it down in plain English so you can keep your tyres pumped and your ride smooth.

What is Tyre Pressure?

Tyre pressure is the amount of air inside your vehicle tyre, measured in units like PSI (pounds per square inch), BAR, or kPa (kilopascals). Each vehicle has its own ideal tyre pressure and running your tyres too high or too low can cause problems.

Common tyre pressure units:

• PSI (pounds per square inch): Most common unit in NZ
• BAR: Used in some parts of Europe
• kPa (kilopascal): Metric unit, also seen in some manuals

Conversion examples: 1 BAR = 100 kPa = 14.5 PSI

Tyre Pressure Conversion Chart

Benefits And Why the Right Tyre Pressure Matters

Having the correct car tyre pressure makes a big difference for your vehicle:

• Safety: Properly inflated tyres give you better grip, handling, and braking. The correct tyre pressure ensures your vehicle responds as it should especially in sudden braking or wet conditions common on NZ roads. Maintaining the right air pressure reduces the chance of losing traction or skidding. Always refer to your vehicle manufacturer’s guide for recommended tyre pressure measurements.

  Read our blog about how to avoid aquaplaning and how to prevent it.

• Fuel Efficiency: Under-inflated tyres create more rolling resistance, which means your car works harder and burns more fuel. This increased rolling resistance not only affects performance but leads to unnecessary fuel costs over time. Keeping the correct tyre pressure reduces friction and helps your vehicle run more efficiently, which is especially helpful on long Kiwi road trips or commutes.
• Longer Tyre Life: Even pressure across the tread helps your tyres wear evenly. With the right pressure measurement, tyres stay in good condition for longer. Over- or under-inflation causes uneven tread wear, costing you more in premature replacements. Even unit of pressure changes (like PSI vs kPa) can make a big difference, so it’s important to follow the vehicle manufacturer’s specifications.
• Comfort: Right pressure = smoother ride. A well-inflated tyre absorbs more of the bumps and potholes that Kiwi roads throw at you. Under-inflated tyres may feel sluggish, while over-inflated ones feel harsh. Using a reliable gauge for regular tyre pressure measurements ensures a smoother, more comfortable ride.
• Better performance: Your car handles as it should, especially in wet or challenging conditions. Whether you’re towing, driving on gravel, or navigating mountain roads, the correct tyre pressure improves handling, stability, and grip. Tyres with balanced air pressure allow your vehicle to respond properly in all driving conditions, giving you more control behind the wheel.

What Happens If Your Tyre Pressure Is Incorrect?

Driving with incorrect pressure can cause:

• Uneven or early tyre wear: Inconsistent air pressure leads to worn tread edges or centres, affecting traction and increasing the risk of a failed WoF. Regular tyre pressure measurements help extend your tyres’ lifespan and maintain safety. Want to learn more about tyre wear? Read our blog on how to read tyre wear patterns.
• Increased fuel consumption: When tyres aren’t inflated to the correct tyre pressure, they drag more on the road due to increased rolling resistance, which forces your engine to use more fuel. Just a few PSI below the recommended level from your vehicle manufacturer can add up over time.
• Poor braking and grip: Under- or over-inflated tyres affect your car’s ability to grip the road especially dangerous in the rain or on loose gravel. Keeping the right unit of pressure ensures better contact with the road and improves stopping distance.
• Higher risk of tyre blowouts: Tyres with incorrect pressure measurement are more prone to heat build-up or rupture. Over-inflated tyres can blow out when hitting a pothole, while under-inflated ones can overheat. Avoid blowouts by regularly checking and maintaining the correct tyre pressure.

What Affects Tyre Pressure?

Several factors influence your vehicle tyre pressure:

• Load: More weight in your car means more pressure may be needed. Carrying heavy loads, towing a trailer, or having extra passengers can put more stress on your tyres. Always check your vehicle manufacturer’s guide for the correct tyre pressure measurements based on your load especially before long roadies or camping trips.
• Driving conditions: Long trips or high speeds can increase tyre temperature and affect pressure. Heat builds up in your tyres the longer and faster you drive, causing air pressure to rise. This is why it’s best to check pressure before a big drive, not during. Keeping your tyres at the correct tyre pressure ensures your car performs safely and efficiently, even on long drives.
• Temperature changes: Cold mornings can drop pressure, while heat can increase it. Tyre air pressure naturally fluctuates with the weather. A drop in temperature can cause pressure to fall, triggering warning lights or affecting handling. It’s a good idea to check regularly, especially during seasonal changes even a small change in unit of pressure (like PSI) matters.
• Tyres are cold or hot: Always check when your tyres are cold for the most accurate reading. Tyres heat up as you drive, which gives an inflated pressure reading. For the most reliable pressure measurement, check them in the morning or after the car has been parked for a few hours. This gives you a true reading and helps you keep things aligned with the correct tyre pressure.

What Should Your Tyre Pressure Be?

There’s no one-size-fits-all number. Most passenger cars need between 30–35 PSI, but always refer to your vehicle handbook or the sticker inside the driver’s door. This tells you the recommended tyre pressure for front and rear tyres.

Pro tip: The spare tyre often needs a different pressure – don’t forget to check that too!

How to Check Your Tyre Pressure

You don’t need to be a mechanic to check your tyre pressure – just follow these simple steps:

1. Get a tyre pressure gauge – digital or manual.
2. Wait until your tyres are cold – at least 2-3 hours after driving.
3. Find the recommended pressure – check your vehicle owner’s manual or door frame.
4. Unscrew the valve cap and press the gauge onto the valve.
5. Read the pressure – compare it with the recommended level.
6. Top up or release air as needed – use a pump at a petrol station or your own air compressor.
7. Screw the valve cap back on – and you’re done!

Handy Tip: Keep a Pressure Gauge in Your Glovebox. They’re cheap, easy to use, and will save you time (and tyres) in the long run.

Quick Recap

Checking your car tyre pressure only takes a few minutes, but it can save you money, improve your fuel efficiency, and keep you safe on the road. Make it part of your regular car care routine, your tyres (and wallet) will thank you!

Got questions? Reach out to our team – we’re here to help you stay safe and sorted.

Happy Motoring!