It breaks down into three key measurements: 245 is the tyre width in millimetres, 35 is the sidewall height as a percentage of the width (a low profile), and R20 means it fits a 20-inch wheel. You will also need to match the load index and speed rating shown after the size to meet your vehicle requirements.
Choose a speed rating that meets or exceeds what your car manufacturer specifies, commonly W or Y for this size on performance vehicles. If your handbook lists a higher rating than your current tyres, follow the handbook. If it lists the same rating, keep it consistent across the axle for predictable handling.
Many 245/35 R20 fitments are specified as XL because the shorter sidewall can need extra load capacity, especially on heavier cars or higher axle loads. Check the load index on your current tyres and your vehicle placard or handbook, then match that requirement. If XL is specified, do not downgrade to a standard load version.
Usually not without confirming manufacturer approval, because the larger sidewall changes the overall rolling diameter and can affect speedometer accuracy, gearing, clearance, and handling balance. If you are considering an alternative size, check the vehicle handbook or speak to a fitter before ordering so the replacement remains within an approved tolerance.
It is best practice to keep the same brand and model across each axle, especially in 245/35 R20 where small differences in tread pattern and stiffness can be felt in steering response. Mixing front and rear can be acceptable if your car is not sensitive to tyre matching, but avoid mixing types on the same axle (for example, different tread patterns or one runflat and one non-runflat). If replacing two, fit the matching pair to the same axle.
