265/40R18 is a wide, low-profile performance tire size often used on sporty sedans, muscle cars, and luxury SUVs.
Meaning
265 → tire width = 265 mm
40 → sidewall height = 40% of the width
R → radial construction
18 → fits 18-inch rims
Common vehicles using 265/40R18
BMW 5 Series
Mercedes-Benz E-Class
Ford Mustang
Chevrolet Camaro
Dodge Charger
Audi A6
Lexus GS