A 315/40R18 is 315 mm wide with a 126 mm sidewall (40 series) on an 18 inch wheel, 27.9 inches tall overall. A tire size only makes sense next to a wheel width and a car. 315/40R18 mounts on a range of widths, and the overall height decides whether the speedometer and the fender stay happy.
3 lines carry 315/40R18, from Nitto. By type that is 3 performance summer. The tire has to stay near your car's stock height and mount on your wheel width, so pick the car and the wheel set and the page keeps only the 315/40R18 lines that do both.
Common questions
What does 315/40R18 mean?
315 is the section width in millimeters, 40 is the sidewall height as a percent of that width (126 mm here), R means radial and 18 is the wheel diameter in inches. Overall the tire stands 27.9 inches tall.
Will 315/40R18 fit your car?
Pick your year, make and model and the tires page answers it for yours. The wheel width has to carry the section width and the overall height has to stay near where the car started.
What wheel width fits 315/40R18?
The tire makers list 8 to 12.5 inch rim widths across the 315 mm sizes we carry, and each product page shows the range for that line. Pick an 18 inch wheel set and the tire step checks the width for you.
