Tyre Pressure, Nitrogen & Tyre Age

What tyre pressure should I run, and does nitrogen make a difference?

Run the cold pressure on the vehicle placard (door pillar or fuel flap), not the maximum on the sidewall, and check it cold. In this climate, temperature swings change pressure more than most drivers expect; nitrogen reduces that drift a little, but correct checking matters far more.

Pressure and temperature

Gas pressure is proportional to absolute temperature. A tyre set to 2.4 bar at 25 °C reaches about 2.8 bar when its air heats to 60 °C — roughly +0.4 bar — and loses it again as it cools. That is why pressure must be set cold, before driving, and why a pressure checked hot after a highway run reads high. Bleeding a hot tyre down to the cold value leaves it under-inflated once it cools.

Under-inflation increases sidewall flexing, heat build-up and wear on both shoulders, and is the main cause of tyre failures at speed. Over-inflation reduces the contact patch and wears the centre.

Nitrogen: real effect

Air is already about 78% nitrogen. Filling with nitrogen removes most of the oxygen and, more importantly, the moisture. Dry gas changes pressure more predictably with temperature, and nitrogen permeates through rubber more slowly than oxygen, so pressure is lost slightly more slowly. On track, consistency is why teams use dry nitrogen. On the road the benefit is modest; checking pressure regularly matters much more.

Mixing tyres

The same model and size on each axle, at minimum; on all-wheel-drive cars, ideally the same model on all four with similar wear. Different tyres have different rolling circumferences and grip, which affects stability control, and on AWD cars a circumference difference makes the centre coupling or differential slip continuously.

Wear, grip, wet and dry

Tyre compounds trade grip against life. A softer compound grips more and wears faster. The UTQG treadwear number (on many tyres) compares wear within one manufacturer’s range; it is not an absolute life figure. Wet grip depends on compound and on tread drainage, and it drops as tread depth falls; dry grip often improves slightly as tread wears. The EU label grades wet grip from A to E, where available. Even premium brands make very different tyres for different purposes, so choose the model and generation, not just the brand.

The 5-year rule and the DOT code

In the UAE, tyres older than five years from their date of manufacture are not allowed on the road, regardless of tread depth. The date is the last four digits of the DOT code on the sidewall: week and year. “2423” means week 24 of 2023, so that tyre reaches five years in week 24 of 2028. Check it before buying — a new tyre can already be a year or two old on the shelf.