Enthusiasts trying to size custom offroad wheels for their vehicle will benefit from Fitment Industries’ video, “How To Choose The Right Tire Size | Tire Sizing Guide.” The video defines how tire style and size are determined and then uses those definitions to determine which non-stock tire sizes you can consider for your vehicle.
The narrator tells us that tire sizes use a combination of metric and standard measures and aspect ratios. He also points out that the wheel width is measured from bead seat to bead seat or an inch wider than the tire’s bead width.
He describes how to determine your desired stretch and the sidewall aspect ratio with that information and advises staying close to the stock height to avoid clearance and speedometer problems.
Finally, the video describes how to enter the information into the Tire Size Comparison Calculator on fitment.com. To stay close to the stock tire diameter, you should work through alternative sizes until you find one that matches or nearly so.
In summary, know your tire size definitions and their relationships to one another, and use tools like the online calculator to identify your ideal tire.