a man checks his tyres are inflated and not deflated.

What are the risks of under inflated tyres?

Driving with under inflated tyres may seem harmless, but if you leave it for too long, it can be dangerous and lead to other problems before you know it!

Identifying under-inflated tyres early could help to improve safety as you get back on the road – read on to find out how under-inflated tyres affect your vehicle, and what you can do about it.

Read on to find out the effects of under inflated tyres, and how you can make sure your car’s rubber stays in tip-top condition.

How under-inflated tyres affect your vehicle

Driving with under-inflated tyres affect many important vehicle systems, including premature tyre wear, fuel consumption, steering and braking ability. You should check your tyre pressures at least once a month to avoid these issues.

Read more about each issue below:

Uneven tyre wear

The sidewalls of the tyre can become misshapen and bulge out because there’s not enough internal air pressure to hold the correct tyre shape. As a result of the sidewalls bulging, the edges of the tyre tread get much more wear than usual because they’re in contact with the ground more often. This can cause premature tyre wear – but if left for too long, excessive wear can lead to tyre bursts in areas where the rubber is too thin to hold the pressure.

If you see any distortions on your tyre and you live close to a tyre fitter, drive carefully at a low speed and get the tyre replaced immediately. If it’s a serious bulge, don’t drive your car and change the wheel if you have a spare, or call your breakdown service provider.

Poor fuel economy

Increased fuel consumption is another by-product of under inflated tyres making more surface contact with the road. When a tyre falls below its recommended inflation pressure, this increased ‘rolling resistance’ means that your engine must work harder to go at the same speed, so you end up using more fuel. It’s been estimated that fuel consumption can increase by up to 5% with a pressure drop of just 7 psi.

Unresponsive steering

Because tyre rubber has more slack in it when it’s in an unpressurised state (or at least a less-pressurised state), your steering will be more sluggish. That’s because it takes more of a side-to-side turn to actually turn the tyre itself. Failing to keep the correct pressure here means that it becomes harder to control your car at speed – it’ll seem like it’s bouncing around bends rather than holding its grip on the road. 

So, not only do under inflated tyres affect your steering, but they also make your car more dangerous to drive. Your ability to brake, make evasive manoeuvres and corner smoothly will all be affected.

Shorter lifespan

It’s been estimated that reduced tyre pressure can create a corresponding reduction in tread life by around 25%-30%. Tyres are expensive items, but crucial to road safety, so it makes sense to look after them. 

TyreSafe, the UK charity dedicated to raising awareness of the importance of correct tyre maintenance and the dangers of defective and illegal tyres, recommends regularly checking your tyres at least once a month and before long journeys. TyreSafe uses an acronym (A.C.T. – Air pressure, Condition, Tread) – the three elements of basic tyre safety checks for every driver.

Five other causes of under inflated tyres

  1. A cut or an embedded sharp item, such as a nail or screw.
  2. Tyres typically lose air naturally (at a rate of up to 2 psi every month) according to Kwik Fit.
  3. A poorly sealed valve or corrosion on your alloy wheel where the tyre is unable to seal correctly around the wheel.
  4. Damage to tyres caused by hitting potholes is becoming increasingly common. 
  5. The drop in temperature during colder months can have a corresponding effect on tyre pressures.

What to do about under-inflated tyres?

There are a couple of options – you can either use a paid air compressor at a petrol station (they’re usually between 50p and £1 to use) or use a 12v compressor at home. It’s a good idea to regularly check your tyre pressures. If you have a 12v compressor, it’ll usually be able to give you a current pressure reading just by putting it onto the valve stem of your tyre. Again, it’s recommended to check your tyre pressures at least once a month

Need to get your tyres checked?

If you need to get your tyres checked or replaced, get in touch with your local Kwik Fit centre. Tyre repair and replacement from Kwik Fit is included as part of your worry-free lease package. 

Find out more about tyre repair and replacement included in your lease

Know your tyre size

Whether they’ve become worn with age or you’ve discovered a puncture, if you find you need a new tyre, the first thing you’ll need to know when replacing it is your tyre size. There are many different tyre sizes depending on the type of car you drive. 

You won’t necessarily find the correct tyre size in the vehicle manual as there are usually several that can be fitted to each make and model of vehicle. The simplest and best way to tell what tyre size you need is to go and have a look at the sidewall of your existing tyre. The sidewall will include lots of letters, numbers and codes, but the one you are looking for is usually in large print and will look a little something like this:

Kwik Fit tyre image.jpg

In this instance the tyre size is 225/45R17 Y. While the numbers and letters may change, the format is always the same e.g. 195/70R14 T or 245/45R19 Y. The numbers and letters each represent a different aspect of the tyre’s size and properties including the tyre width, aspect ratio, rim size and speed rating. 

When looking for the tyre size on the sidewall of your tyre, make sure you look at the markings on the tyre that needs replacing as they may not all be the same. On many makes and models of vehicle, the front and rear tyre size can actually be quite different in order to improve handling and stability. Tyres on the same axle should always be the same size however.  

About the Motability Scheme

The Motability Scheme supports families in staying mobile by offering a unique, all-inclusive leasing package for brand new cars from all the major manufacturers. If you care for a child or someone who doesn’t drive, you can be added as a named driver instead. And as well as cars from a range of manufacturers, cars with adaptationsWheelchair Accessible Vehiclesscooters and powered wheelchairs are available too.

If you’d like to find out more about the Scheme, request an information pack below and we’ll send you all the information that you need to make the right choice. 

Get a free information pack


Related articles

What to expect when visiting a Kwik Fit centre

Tyres fitted at home: a closer look at Kwik Fit’s mobile service

Everything you need to know about servicing your Motability Scheme car


From the Motability Scheme


Popular articles