About This Calculator
Wheel offset decides where a wheel sits on the hub. A small change can move the rim toward suspension parts. It can also push the face toward the fender. This calculator compares two setups side by side. It shows the practical movement in millimeters. It also explains tire diameter changes when tire sizes are entered.
Why Offset Matters
Offset is the distance from wheel centerline to mounting face. Positive offset places the mounting face outward. Negative offset places it inward. Wider wheels also change clearance, even when offset stays the same. That is why width and offset must be reviewed together. A new wheel may look similar online. It can still rub a strut, liner, brake part, or fender lip.
What The Results Show
Inner change describes movement toward or away from suspension. A positive value means the new wheel sits closer inside. A negative value means more inner space. Outer change describes poke. A positive value means the new wheel sticks outward more. Track change doubles the outer movement for both sides. Effective offset includes any spacer value entered. A spacer reduces effective offset and usually increases poke.
Tire Size Effects
Wheel fitment also depends on tire section width and aspect ratio. The tire calculation estimates sidewall height, total diameter, circumference, ride height change, and speedometer error. A taller tire may fill the arch better. It may also rub during turning or compression. A shorter tire may improve clearance. It can create a larger arch gap. Speedometer error helps compare rolling diameter before installation.
Helpful Fitment Tips
Measure existing clearance before ordering parts. Check inner barrel clearance, fender space, brake caliper room, and steering lock. Remember that tire brands can vary in real width. Alignment, camber, load, suspension travel, and body condition also matter. Use the calculator as a planning guide. Final fitment should be confirmed by test fitting, safe torque procedures, and professional inspection when clearance is tight.
Common Mistakes
Do not judge fitment by offset alone. Two wheels can share the same offset and sit differently. Always convert width to millimeters. Include spacers in the effective offset. Compare each side of the vehicle. Leave room for heat, flex, passengers, cargo, road bumps, and safety.