Car manufacturers recommend tyre sizes, which you'll find in the notebook or doorsill. These dimensions are approved and ensure maximum performance for your vehicle. You can use any of options given by the manufacturer without any worries.
If you use something that hasn't been approved, you may no longer be in compliance with the legislation, be issued with a follow-up inspection during your MOT, or have problems with your insurance in case of an accident.
However, you may still want to change the size of your tyres to a size not approved by the manufacturer. If you choose to do so, you must choose the right width and the right theoretical equivalence according to the data in the table available HERE.
| Rim width | Minimum tyre width | Ideal tyre width | Maximum tyre width |
|---|---|---|---|
| 5.0 Inches | 155 mm | 165 or 175 mm | 185 mm |
| 5.5 Inches | 165 mm | 175 or 185 mm | 195 mm |
| 6.0 Inches | 175 mm | 185 or 195 mm | 205 mm |
| 6.5 Inches | 185 mm | 195 or 205 mm | 215 mm |
| 7.0 Inches | 195 mm | 205 or 215 mm | 225 mm |
| 7.5 Inches | 205 mm | 215 or 225 mm | 235 mm |
| 8.0 Inches | 215 mm | 225 or 235 mm | 245 mm |
| 8.5 Inches | 225 mm | 235 or 245 mm | 255 mm |
| 9.0 Inches | 235 mm | 245 or 255 mm | 265 mm |
| 9.5 Inches | 245 mm | 255 or 265 mm | 275 mm |
| 10.0 Inches | 255 mm | 265 or 275 mm | 285 mm |
| 10.5 Inches | 265 mm | 275 or 285 mm | 295 mm |
| 11.0 Inches | 275 mm | 285 or 295 mm | 305 mm |
| 11.5 Inches | 285 mm | 295 or 305 mm | 315 mm |
| 12.0 Inches | 295 mm | 305 or 315 mm | 325 mm |
| 12.5 Inches | 305 mm | 315 or 325 mm | 335 mm |
