[As Pic 15 Inch]
Size overview:
Tyre covers size 14 inches fits tyre diameter 60 - 69 cm.
Tyre covers size 15 inches fits tyre diameter 70 ~ 75 cm.
Tyre covers size 16 inches fits tyre diameter 76 ~ 79 cm.
Tyre covers size 17 inches suitable for tyre diameter 80 - 83 cm.
How do you calculate your tyre diameter?
Step 1: Find your tyre parameter. It says on your tire side
Step 2: Calculate your tire diameter
If your tyre is written with P215/60R16, A=215 B=60 C=16.
Tyre diameter: A*B/500 +C*2.54 = 215*60/500+16*2.54 = 66.44 cm.
You need to buy the 14 inch cover.