225 45R18 tyres have a 225mm width and an aspect ratio of 55%. The aspect ratio is the height of the tyre in comparison to its width. The R means that the tyres are made with radial ply construction and suit wheel rims with diameters of 18 inches. Tyres have one last part of their code that represents the maximum load capacity for each tyre and the top speed that they can travel at. A 225 45 R18 91Y can carry 615kg per tyre at up to 300km/h.
225 45R18 run flat tyres are just one of many options. These tyres allow you to keep driving for a short distance until you can get them changed over. They suit a range of different small 4WDs, hatchbacks, wagons and sedans.
Some common cars that can use 225 45R18 tyres include the Audi A4, the BMW 3 Series, the Holden Malibu, the Honda XR-V, the Hyundai Sonata, the Mazda 6, the Mercedes-Benz C-Class and the Nissan Maxima.
Other tyres may suit your driving style better than the 225 45 R18. Something with more width like the 235 40 R18 would have a shorter stopping distance and better handling.