Wheel Fitment Calculator

Compare an aftermarket wheel and tire to your OEM setup: poke, inner clearance, backspacing, optional spacers, and similar real-world Modified1 builds. Geometry only — not a fit guarantee.

MakeModelYear

OEM / current wheel

Diameter (in)Width (in)Offset (mm)

Tire (optional) e.g. 235/40R18

Proposed wheelUse different rear setup

Diameter (in)Width (in)Offset ET (mm)

Tire (optional)Spacer (mm) — does not rewrite wheel ET

Inner / suspensionFender / outer

OEMProposed

Calculated geometry

Compared with your OEM wheel: 18×8 ET50 → 18×9.5 ET35

Outer edge: 34 mm farther toward fender (more outward poke) (+34 mm)
Inner edge: 4 mm closer to suspension (less inner clearance) (+4 mm)
Wheel width: +1.5 in
Offset: ET50 → ET35
Backspacing: 5.97 in → 6.13 in (+0.16 in)

Geometry only. This does not mean the wheel “fits,” “clears,” or is “safe” on your car.

Solve offset from backspacing (legacy)