It breaks down into the tyre width (245 mm), the profile (45% of 245 mm), the construction (R for radial), and the wheel diameter (21 inches). You will also see a load index and speed rating after the size, and those must meet or exceed the vehicle manufacturer requirement. Match the full size exactly and confirm the load and speed codes on your current tyres or the vehicle placard before ordering.
Use the ratings shown on the driver door sticker or the handbook, as they are set for your vehicle weight, axle limits and intended top speed. This size is often fitted to heavier, higher-power vehicles, so higher load indexes and W or Y speed ratings are common. You can usually fit a higher load index, but you should not fit a lower one, and you should never drop below the specified speed rating.
Summer tyres suit warmer conditions and prioritise dry and wet grip at typical UK spring and summer temperatures. Winter tyres are designed for colder weather and are the safest option if you regularly drive when temperatures drop below about 7C. All-season tyres are a popular choice in this size for year-round use, and choosing a version marked 3PMSF gives extra reassurance in wintry conditions.
Yes, many options are available with reinforced construction, often labelled XL, which is commonly specified for SUV and crossover applications in this size. Run-flat versions also exist in selected tyre ranges, but they should only be chosen if your vehicle is designed for them or your manufacturer approves the switch. If you move away from run-flats, plan your puncture solution in advance so you are not left without mobility.
For many AWD systems, replacing all four together is the safest approach because it keeps rolling circumference and grip consistent across axles. If you only replace two, keep tread depths as closely matched as possible and follow the vehicle manufacturer guidance on which axle should receive the new tyres. Aim to keep the same brand and tread pattern across the vehicle where you can, as it helps maintain predictable handling and traction.
