How would under inflated tyres affect a vehicle?

It’s easy to forget about tyre pressure until something goes wrong. But driving with under-inflated tyres can have serious effects on your car’s performance, safety and fuel efficiency. Knowing what under-inflated tyres do to your vehicle could save you from expensive repairs or even a dangerous breakdown. 

In this guide, we’ll explain what under-inflated tyres mean, how they affect your car, how to inflate tyres correctly at a petrol station, and when to check them. 

What is an Under-Inflated Tyre? 

An under-inflated tyre is a tyre that contains less air pressure than recommended by the vehicle manufacturer. Every vehicle has an ideal tyre pressure range, usually measured in PSI (pounds per square inch), and driving below this range can affect your vehicle’s performance in more ways than one. 

To find your car’s recommended tyre pressure, check the sticker usually located inside the driver’s door frame or refer to your vehicle’s handbook.

 

6 Ways Under-Inflated Tyres Influence Your Vehicle  

Under-inflated tyres put more rubber in contact with the road than intended. This leads to a range of knock-on effects that can reduce safety and performance.  

Here’s what to expect: 

1. Poor Handling and Steering 

Your car may feel sluggish or unresponsive when cornering a bend. The extra pressure in the tyre wall makes your steering feel bouncy and imprecise, especially at higher speeds. This is very dangerous, and you should pull over at the safest and earliest convenience.  

2. Longer Braking Distances 

Under-inflated tyres compromise grip, which means your car won’t stop as quickly in an emergency. This increases your stopping distance, particularly in icy or wet conditions. 

3. Increased Fuel Consumption 

When tyres are soft, your engine must work harder to move the vehicle, which means you burn more fuel. Over time, this can noticeably reduce your MPG (miles per gallon) and gradually cost you more when filling up at the petrol station. 

4. Uneven and Faster Tyre Wear 

Under-inflation causes the outer edges of the tyre tread to wear more quickly than the centre. This shortens the life of your tyres and increases the chances of needing a full set sooner than expected. 

5. Greater Risk of Blowouts 

Tyres that are too soft can overheat more easily, especially at motorway speeds. This raises the risk of a sudden blowout, which can be dangerous as your car becomes difficult to control and puts you and other drivers at risk.  

6. Damage to Suspension and Alignment 

Excess tyre flex places more strain on your vehicle’s suspension components. This can lead to premature wear and tear on shocks, struts, and wheel alignment. 

 

How to Inflate Tyres at a Petrol Station 

Follow these steps: 

1. Find your recommended tyre pressure by checking the driver’s side door sticker or your handbook. 
2. Remove the dust cap from the tyre valve. 
3. Use the air machine to input your desired PSI. 
4. Attach the nozzle and wait for the beep or gauge to confirm it’s pressurised correctly. 
5. Replace the cap and repeat for all tyres, including the spare if needed. 

It’s best to check your tyre pressure when tyres are cold, as pressure rises when driving. 

 

How Often Should I Check My Tyre Pressure? 

You should check your tyre pressure at least once a month and always before a long journey. This is particularly important in colder weather, where temperature drops can cause tyre pressure to fall naturally. 

 

How Do I Know If My Tyres Are Under-Inflated? 

• The TPMS warning light on your dashboard is often the first clue. 

• Your tyre looks visibly flatter at the bottom. 

• Your steering may feel heavier, or the car may pull slightly to one side. 

• Fuel consumption increases even though your driving habits haven’t changed. 

• You hear more road noise than usual. 

Under-inflated tyres may seem like a minor issue, but they can have a major impact on how your vehicle performs. By checking your tyre pressure regularly and knowing what signs to look out for, you’ll drive more safely and save money on fuel and tyre replacements. 

If you're unsure about your tyre pressure or want a free check, visit your nearest Merityre fitting centre. Our experts are on hand to help keep your tyres in pristine condition – all year round. 

 

FAQs 

Can under-inflated tyres fail an MOT? 

Yes. If tyre pressures are significantly incorrect or if wear is uneven and dangerous, this can lead to an MOT failure. 

What is the legal minimum tyre tread depth in the UK? 

1.6mm across the central three-quarters of the tyre. Under-inflation can cause uneven wear, pushing your tread depth below legal limits faster.