Tyre Pressure and Fuel Economy: A Simple Check That Saves Money

Of all the things you can do to reduce fuel use, checking tyre pressure is the cheapest and one of the most effective. It takes five minutes, costs little or nothing at most pumps and workshops, and also makes your tyres last longer and your vehicle safer.

Why pressure affects fuel use

A tyre that is soft has a larger area in contact with the road and flexes more as it turns. That extra flexing creates heat and drag, called rolling resistance, and the engine must burn more fuel to overcome it. A properly inflated tyre rolls more freely. The effect is gradual, so many drivers never notice it, but over thousands of kilometres it shows up in the fuel bill.

Other reasons to keep tyres inflated

• Longer tyre life. Low pressure wears the edges of the tread faster, and a tyre may need replacing earlier than necessary.
• Better handling and braking. A tyre at the right pressure holds its shape, which improves grip and stability.
• Safety. Running at low pressure makes overheating more likely, especially in hot weather and with heavy loads, and overheated tyres are more likely to fail.

Find the right pressure

Do not use the number printed on the tyre sidewall. That is the maximum the tyre can hold, not the pressure recommended for your vehicle. The correct figure is in the owner's manual and often on a sticker on the driver's door frame or inside the fuel flap on cars. On motorcycles, look in the manual or on a sticker near the swingarm or chain guard. Motorcycles often have different pressures for the front and rear, and for riding with a passenger.

How to check, step by step

1. Check the tyres when they are cold, meaning the vehicle has been parked for a few hours or has been driven for less than a couple of kilometres. Driving heats the air inside and raises the reading.
2. Remove the valve cap and press a reliable gauge firmly onto the valve.
3. Read the pressure and compare it with the recommended figure.
4. Add or release air until it matches, and replace the valve cap.
5. Check all tyres, including the spare, which is easy to forget.

Buy a small gauge of your own if you can. Gauges at some stations are worn or inaccurate, and a basic one costs little. It also lets you check before a long trip.

How often to check

Check at least once a month and before any long journey. Tyres lose a little air naturally, and the loss is faster in hot weather and with small punctures. A sudden drop in one tyre compared with the others suggests a leak that needs repair.

Do not over-inflate

More air is not better. Over-inflated tyres have a smaller contact patch, wear in the middle of the tread and give a harsher ride and less grip, especially on wet roads. Always stay at the recommended pressure, and add a little only when the manual recommends it for heavy loads or high-speed driving.

Nitrogen and other claims

Some workshops recommend filling tyres with nitrogen. It can reduce the rate at which pressure falls slightly, but ordinary air is already about 78 per cent nitrogen, and the benefit for everyday vehicles is small. The important habit is checking pressure regularly, whichever gas is in the tyre.

What can you save

The exact figure depends on the vehicle and how low the tyres were. Suppose proper inflation improves a car's mileage by a modest three per cent. A car covering 1,000 km a month at 12 km per litre uses about 83.3 litres, and a three per cent saving is about 2.5 litres, or roughly Rs 1,000 a month at an illustrative price of Rs 400 per litre. That is Rs 12,000 a year, before counting the longer life of your tyres. For a motorcycle the amounts are smaller, but the percentage is similar, and a rider who spends Rs 7,800 a month on fuel could keep a couple of hundred rupees. Use our fuel calculator with your own numbers.

Make it a habit

Pick a regular date, such as the first Sunday of each month, and check all tyres. Write the pressures in your fuel log so that you can see a trend. If a tyre keeps losing air, have a workshop inspect the tyre and valve instead of simply refilling it.

Common questions about tyre pressure

Should I add air in hot weather? Pressure rises when the tyre is warm, so measure when it is cold. Do not let air out of a warm tyre to bring it down to the cold figure. Heat raises the reading, but the cold pressure is what the manual specifies.

What if my tyre pressure warning light comes on? Check all the tyres with a gauge as soon as it is safe. If one is low, look for a nail or a leaking valve. Do not keep driving on a flat or very soft tyre, since it can be damaged beyond repair.

Does a heavy load change the pressure I need? Many manuals give a higher pressure for a fully loaded car or for long high-speed trips. Check yours. For a motorcycle, a passenger usually calls for a higher rear pressure.

Signs your tyres need attention

Look at the tread across the whole width. Wear on both edges suggests under-inflation, and wear down the centre suggests over-inflation. Wear on one edge only suggests alignment trouble. Bulges, cracks in the sidewall, objects stuck in the tread and a tread depth near the wear indicators mean the tyre should be inspected or replaced. A good tyre that is properly inflated is one of the best investments in fuel economy and safety that you can make.

Tyre pressure is one part of a wider set of efficiency habits. See our guides on fuel-efficient driving and maintenance habits that improve mileage, and for motorcycles, getting more kilometres per litre from a motorcycle.