Decode tyre load index and speed rating. Check max load, recommended inflation and whether tyres are rated for your vehicle GVM.
Load index 91 means each tyre can carry a maximum of 615 kg at the recommended inflation pressure. Four tyres at LI 91 support up to 2,460 kg total — suitable for most passenger vehicles up to that GVM.
Tyre pressure is specified on the vehicle placard (usually in the driver's door jamb or fuel cap). Typical passenger cars use 200–240 kPa (29–35 PSI) cold. SUVs and utes may use higher pressures, especially when loaded. This calculator provides an estimate; always verify against the vehicle placard.
Underinflation causes excessive sidewall flexing, generating heat that can cause tyre failure. It also increases fuel consumption, reduces handling response and shortens tyre life. A tyre at 80% of its recommended pressure can run 20–30°C hotter than a properly inflated one.