How Wheel Offset Affects Handling, Scrub Radius and Bearing Life

Wheel offset changes where the tire's contact patch sits relative to the steering axis. That distance is called scrub radius — and it controls a surprising amount of how the car feels through the wheel.

Positive scrub radius (contact patch outboard of the steering axis) is the OEM default on most modern cars. It gives stable straight-line behaviour and predictable feedback. Zero scrub radius is used on some performance cars for the cleanest steering feel but tends to feel 'dead' at the limit. Negative scrub radius is rare on factory cars but appears on some race setups.

When you reduce offset (push the wheel outboard), the contact patch moves outboard too. Scrub radius increases. Steering effort grows, bump-steer becomes more sensitive, and the car may tramline (follow road ruts) more aggressively. The wheel also fights you slightly under braking on uneven surfaces.

When you increase offset (tuck the wheel inboard), scrub radius decreases. Steering feel becomes lighter, sometimes vaguer. On front-wheel-drive cars with torque steer, large offset changes can make torque pull through the steering wheel noticeably worse or better depending on direction.

Wheel bearings carry both vertical load (vehicle weight) and lateral load (cornering forces). Offset changes the lever arm by which lateral load passes through the bearing. Lower offset increases the moment, accelerating wear on the outer race. A common mechanic estimate is that ET changes beyond ±15 mm halve typical bearing life.

Bump-steer is the unwanted steering input that occurs when the suspension compresses. Offset interacts with bump-steer because the tie-rod-to-steering-knuckle geometry was designed around a specific contact patch location. Big offset changes shift that geometry without the designer's knowledge, so the car may steer slightly as you hit a bump.

Rubbing is the most obvious handling effect. Lower offset rubs the fender at full lock or full suspension compression; higher offset rubs the strut, brake caliper or upper control arm. Both are unsafe — fender rub damages the tire, strut rub damages the wheel or suspension.

How much change is safe? Within ±5 mm of OEM ET, almost no driver will notice anything other than appearance. Within ±10 mm, mild changes in feel and tire wear. Beyond ±15 mm, you are re-engineering the suspension — get aligned, expect faster bearing wear, and verify clearance with full lock and full compression checks.

Use the wheel offset calculator to quantify exactly how a new ET will shift the contact patch on your car. The poke, inner clearance and track-width change figures are deterministic; the handling consequences scale with how far you push beyond OEM.