The tyre options available for the Kia Optima on Tyres.co.uk include the Michelin Primacy 5 and the Goodyear EfficientGrip Performance 2, both of which are available in 215/55 R17 for 17-inch-wheel factory versions. Before placing an order, please check the registration for the original size, load index, speed rating, and any XL requirements on the driver's door placard.
You can find the Kia Optima's tyre size on the tyre-and-loading placard located on the driver's side centre pillar (B-pillar) just inside the driver's door. To see the tyre size along with the necessary load and speed ratings and cold pressure limits, check the owner's manual and the sidewall of the fitted tyre.
As a general rule, all four tyres do not need to be replaced on a Kia Optima as UK-market examples are front wheel drive and do not have an all-wheel-drive system that would require four identical tyres. If possible, replace tyres on an axle pair basis, matching specification across the axle; UK tyre safety guidance dictates that when placing two new tyres, they should be fitted to the rear axle.