Current vs proposed setup
Enter two tyre or tire sizes plus wheel width and offset. The calculator shows diameter, speedometer impact, and nominal movement toward the suspension and fender.
Setup inputs 205/55R16 → 225/45R17 Edit
Results are dimensional estimates, not a vehicle-specific fitment approval. Verify brake, hub, suspension, fender, load and tire-manufacturer requirements physically before purchase.
How to use the wheel and tire fitment calculator
Enter the size printed on each tire sidewall, followed by the stamped wheel width and offset. For example, compare a current 205/55R16 tire on a 16×8 ET35 wheel with a proposed 225/45R17 tire on a 17×9 ET45 wheel.
Understand the result
Diameter change affects ride height, arch gap, revolutions per distance and the estimated road speed for a given speedometer reading. Wheel width and effective offset determine how the nominal inner and outer rim edges move relative to the hub mounting face.
Formula assumptions
Theoretical tire diameter equals rim diameter plus two calculated sidewalls. Effective offset equals stamped offset minus spacer thickness. Actual mounted tire dimensions vary by tire model, pressure, load and measuring rim.
Measured-clearance mode
If you enter an existing static gap, the calculator subtracts movement toward that side to estimate the remaining gap. This cannot account for brake shape, steering lock, camber, tire deformation, suspension compression or body movement.
Always verify on the vehicle
Confirm bolt pattern, centre bore, fastener seat, brake clearance, load and speed ratings, tire-to-rim approval, and clearance throughout steering and suspension travel. Consult the vehicle and component manufacturers or a qualified wheel-and-tire professional.