Positive offset
+40 mm
On the same width, the wheel sits further inward compared with a lower offset.
On this page
Tire & wheel guide
Wheel Offset Explained: Positive, Negative & Zero Offset
Wheel offset is the distance between the wheel’s hub-mounting surface and the wheel centerline, typically expressed in millimetres. It does not, by itself, confirm tire or fender clearance.
What offset measures
Wheel offset is the distance between the wheel centerline and the hub mounting face, measured in millimetres.
What wheel offset means
Offset places the wheel relative to the hub. Combined with wheel width, it determines how far the inner and outer rims sit. Most modern passenger and crossover wheels use positive offset; that is a packaging fact, not a quality ranking.
Positive, zero, and negative offset
The same wheel cross-section; only the hub mounting face moves relative to the centerline. Orientation stays consistent: outboard (street) on the left, inboard (vehicle) on the right.
Zero offset
0 mm
The hub mounting face sits on the wheel centerline.
Negative offset
−20 mm
On the same width, the wheel sits further outward compared with a higher offset.
These diagrams describe geometry only. They do not recommend an offset for any vehicle.
Why wheel width matters
Offset is measured from the centerline. A wider wheel at the same offset extends farther outboard and inboard because added width is distributed around that centerline.
18×8 +40 → 18×9 +40 (width only)
Outer: +12.7 mm · 12.7 mm farther outward
Inner: +12.7 mm · 12.7 mm closer to suspension
Worked example
Original 18×8 +40 mm versus new 18×9 +25 mm, using the same helper as the Wheel Offset Calculator.
Original
18×8 +40 mm
New
18×9 +25 mm
Offset change
-15 mm
15 mm lower offset
Outer poke
+27.7 mm
27.7 mm farther outward
Inner position
-2.3 mm
2.3 mm more inner clearance
Original backspacing
5.57 in
Hub face → inner lip (original)
Wheel position change
Depends on offset change + half of width change
Exact signed poke and inner-position values use the calculator helpers — open the tool for your widths and offsets.
Offset vs backspacing
TireReference converts with the same functions as the calculator: backspacing = width/2 + offset/25.4. For 8 inches and +40 mm, backspacing is 5.57 in.
Offset
Measured from wheel centerline to hub mounting face
Unit: mm
Example: +40 mm
Backspacing
Measured from hub mounting face to inner wheel lip
Unit: inches
Example: 5.57 in
Does lower offset mean more poke?
On the same width, yes. Once width also changes, poke is the combined effect — as in the 18×8 +40 versus 18×9 +25 shopping case above.
18×8 +40 → 18×8 +25
Offset -15 mm · outer +15 mm
Tire width and offset together
Separate wheel geometry from the tire envelope. Offset positions the wheel; section width builds clearance around it.
FAQ
What does +35 offset mean?
+35 mm means the hub mounting face is 35 millimetres toward the wheel face from the wheel centerline (positive offset).
What is zero offset?
Zero offset means the hub mounting face sits on the wheel centerline.
Does lower offset mean more poke?
On the same wheel width, a lower (more negative or less positive) offset moves the wheel outward. Wheel width also changes inner and outer position, so offset alone does not define poke.
Is offset the same as backspacing?
No. Offset is hub face to centerline (usually mm). Backspacing is hub face to the inner rim lip (usually inches). For an 8-inch wheel at +40 mm, TireReference backspacing is 5.57 in.
Does wheel width affect offset?
Offset is still measured from centerline to hub face. Changing width with the same offset moves both the inner and outer lips. Width and offset must be considered together.
What happens if offset is too high?
Higher positive offset moves the wheel inward relative to the same width, reducing inner clearance toward suspension and brakes. Whether that is “too high” is vehicle-specific and is not certified here.
What happens if offset is too low?
Lower (less positive or more negative) offset moves the wheel outward on the same width, increasing poke toward the fender. Whether that is “too low” is vehicle-specific and is not certified here.
Related tools
Poke, inner clearance, and backspacing on this page are produced by the Wheel Offset Calculator helpers. OEM wheel-offset values are omitted because the current OEM dataset is tire-size fitment, not wheel offset. See TireReference Data & Calculation Standards.