Correct tyre pressure is one of the simplest, cheapest and most important aspects of vehicle maintenance — yet it is also one of the most frequently neglected. Incorrect tyre pressure directly affects your safety, fuel economy and tyre life.
Why Tyre Pressure Matters
Your tyres support the entire weight of your vehicle on a cushion of compressed air. The pressure determines how the tyre deforms under load and how the contact patch — the area of rubber touching the road — behaves.
Running tyres at just 10% below recommended pressure can increase wear rate by up to 15% and increase fuel consumption by up to 3%. Across a fleet or high-mileage vehicle, these figures add up to significant money.
How to Find the Correct Pressure for Your Vehicle
The correct tyre pressure for your vehicle is specified by the manufacturer — not by the maximum pressure shown on the tyre sidewall, which is the maximum permissible pressure, not the recommended operating pressure.
Find the correct pressure in your vehicle’s owner’s handbook, or on the tyre pressure label found inside the driver’s door jamb or on the fuel filler flap. Most vehicles show different pressures for front and rear tyres, and often have different recommendations for normal load and full load.
When to Check Tyre Pressures
Check tyre pressures at least once a month and always before any long journey. Critically, always check when the tyres are cold — meaning the vehicle has been stationary for at least two hours and has not been driven more than a couple of miles.
Tyre pressure increases as tyres warm up during driving. Checking hot tyres and deflating to the cold pressure figure will result in dangerous under-inflation when the tyres cool.
The Effects of Under-Inflation
- Rapid wear on the outer shoulders of the tyre
- Increased fuel consumption — more rolling resistance
- Poor handling and reduced braking performance
- Increased risk of sudden tyre failure from impact damage
- Overheating of the tyre structure, which can cause catastrophic failure
The Effects of Over-Inflation
- Rapid wear on the centre of the tyre tread
- Reduced contact patch — less grip
- Harsher ride — more susceptible to pothole damage
- Reduced braking effectiveness
Tyre Pressure Monitoring Systems (TPMS)
All new vehicles sold in the UK since November 2014 are required to have a tyre pressure monitoring system. TPMS warns you when pressure drops significantly — but only once it has fallen by around 25%. This means a tyre can be significantly under-inflated before any warning appears.
TPMS is a useful safety net but it does not replace regular manual checks. Do not rely on the warning light to tell you when your tyres need attention.
North Wales Specific Consideration
The varied terrain of North Wales — from coastal roads to mountain passes — means tyre pressures are especially important. On mountain routes like the Llanberis Pass, Horseshoe Pass or the A470 through Snowdonia, the combination of steep gradients, tight corners and variable road surfaces puts additional demands on your tyres. Correct pressure is essential.
Need Help with Your Tyres?
If you discover your tyres are significantly under or over-inflated, or if a tyre needs replacing, Mobi Tyre can reach you across North Wales and border England within 45-60 minutes. Call 07768 491888 — available 24 hours a day, no call-out charges.
