Guide
Plus-Sizing Guide: How to Upgrade Wheel Size Safely
Plus-one and plus-two upgrades done right — keeping rolling diameter constant, picking the right tire width and offset, and knowing the comfort tradeoffs.
Key takeaways
- Plus-sizing means fitting a larger-diameter wheel with a lower-profile tire so the overall rolling diameter stays close to the original.
- The core rule is to keep overall tire diameter within ±3% of the OEM size.
- As wheel diameter goes up, sidewall height must go down to compensate.
Main explanation
Plus-sizing means fitting a larger-diameter wheel with a lower-profile tire so the overall rolling diameter stays close to the original. Plus-one is a one-inch wheel increase (e.g. 16 to 17), plus-two is two inches. Going beyond plus-two on a passenger car is rarely worthwhile.
The core rule is to keep overall tire diameter within ±3% of the OEM size. That keeps the speedometer, ABS and traction control inside their normal calibration tolerance. Use the comparison calculator to verify any combination before buying.
As wheel diameter goes up, sidewall height must go down to compensate. Lower sidewalls transmit more impact force, so ride comfort degrades, road noise increases and pothole damage to wheels becomes more likely. Plus-one is usually a comfortable daily compromise; plus-two is firmer and best on smooth roads.
Wheel width and offset matter as much as diameter. A wider wheel with the same offset moves outward AND inward by half the width gain — so inner clearance to the strut is often the limit before fender poke. Pick a tire width inside the wheel manufacturer's recommended range to avoid stretched or bulged fitment.
Speedometer impact is small if rolling diameter is preserved within 1–2%, but any change above 3% is noticeable and may affect mileage logged on the odometer. The speedometer error calculator gives a precise figure for the exact two sizes you are considering.
Before plus-sizing, always check: load index meets or exceeds the placard, speed rating meets or exceeds the placard, the new tire is rated for the new wheel width, fender and strut clearance with full lock and full bump, and that the wheels meet your country's protrusion or fender-cover regulations.