Tyre upsizing is a good way to enhance the performance and looks of your vehicle. But installing too big tyres on your car can sometimes negatively affect the handling. Tyre upsizing also results in the speedometer error. As a general rule, the diameter variation between the two tyre size should be under 3%. We have built this easy to use tyre upsize calculator for you, just enter the size of your OEM tyre and the tyre size you want to upgrade to:
How to Read Tyre Size?
The tyre size, load rating and speed rating in mentioned on the sidewall of the tyre. Example: 185/65R15 88T. Let’s see what these markings stand for:
1) Tyre Width: The first three numbers here represent tyre width in millimetres. In the above example, tyre width is 185mm.
2) Aspect Ratio/Profile: This number is used to gauge if the tyre will be high profile of low profile (height of sidewall). It is represented by two digit number after the slash mark. This number is the ratio of height of tyre’s cross-section to its width. In the above example, the tyre profile/height will be equal to 65% of 185 (tyre width).
3) Type of Tyre: There are 3 types of tyre construction: Bias Belt, Diagnol cross-ply, and Radial. The “R” letter here stands for radial tyre.
4) Rim Diameter: The two-digit number after this represents the diameter of the rim on which this tyre will be mounted. In above example, rim diameter is 15 inches.
5) Load Index: The next two-digit number after space tells the load rating on the tyre.
6) Speed Rating: The Speed rating of the tyre is represented by the letter at the end. The speed rating of the tyre should always be more than the top speed capability of the car. In the example, the speed rating is represented by “T”.
Play the Video Below to Learn How to Read Tyre Markings
Common Tyre Sizes Available in India
| 12 Inch Tyre | 13 Inch Tyres |
| 145/80R12 | 145/80R13 155/65R13 155/70R13 155/80R13 165/65R13 175/70R13 185/70R13 |
| 14 Inch Tyres | 15 Inch Tyres |
| 155/65R14 165/65R14 165/70R14 165/80R14 175/65R14 175/70R14 185 R14 185/60R14 185/65R14 185/70R14 195/60R14 195/70R14 | 175/65R15 185/60R15 185/65R15 195/60R15 195/65R15 205/60R15 205/65R15 215/70R15 235/75 R15 31X10.50R15 |
| 16 Inch Tyres | 17 Inch Tyres |
| 195/55R16 195/60 R16 205/50 ZR16 205/55R16 205/60R16 215/55R16 215/60R16 215/65 R16 215/65R16 225/50ZR16 225/55R16 225/60 R16 235/60R16 235/70 R16 245/70 R16 | 205/45ZR17 215/45R17 215/50ZR17 215/55R17 215/60R17 225/45ZR17 225/50 R17 225/50ZR17 225/55 R17 225/55R17 225/65R17 235/55R17 235/60 R17 235/65 R17 235/65R17 245/45R17 255/60 R17 265/65 R17 |
| 18 Inch Tyres | 19 Inch Tyres |
| 225/40ZR18 235/40R18 235/45R18 235/60R18 245/40R18 245/40ZR18 245/45R18 245/45R18 245/50R18 255/45R18 255/55R18 255/55R18 255/55R18 265/60R18 285/60R18 | 245/40R19 245/45R19 245/45R19 255/50R19 255/50R19 275/35R19 |
| 20 Inch Tyres | 21 Inch Tyres |
| 275/45R20 | 265/40R21 275/30R21 275/35R21 285/30R21 285/35R21 |
How is Tyre Upsizing Calculated?
Diameter of two tyre size is compared to each other. The size variation between them needs to be under 3%. Tyre diameter is calculated by adding rim size with (tyre sidewall height x 2).
What are the Benefits of Tyre Upsizing?
Tyre upsizing can be great for enhancing looks and road traction of your vehicle.
What are the disadvantages of Upsizing?
Some of the drawback of tyre upsizing can be increased tramlining effect, weighted steering wheel, decreased fuel efficiency, and more road noise. Therefore, use this tool to choose the right tyre size.