How To Find The Offset Of A Wheel | Read Numbers Right

Wheel offset is the distance from the hub pad to the wheel centerline, usually stamped as ET or offset in millimeters.

Finding wheel offset gets easier once you know what the number means and where wheel makers usually stamp it. In most cases, you do not need special tools. You need a clean wheel, good light, and a clear read of the markings on the back of the spokes or barrel.

If the stamp is gone, worn off, or hidden under grime, you can still work it out with a straightedge and tape measure. That gives you a usable number before you buy tires, order spacers, or swap to a wider wheel. A small offset change can move the wheel inward toward the strut or outward toward the fender, so getting the number right saves a lot of grief.

How To Find The Offset Of A Wheel From Stamped Marks

The fastest path is the stamp cast or forged into the wheel. Offset is usually shown in millimeters and often appears as ET, +35, -12, or the word OFFSET followed by a number. On many aftermarket wheels, that stamp sits on the back of a spoke, near the hub pad, or inside the barrel.

A marking such as 18×8.5 ET45 tells you three things at once: diameter, width, and offset. In that case, the wheel is 18 inches across, 8.5 inches wide, and has a positive 45 mm offset. Wheel makers use this format because width without offset does not tell you where the wheel will sit once it is bolted on.

If you want a clean visual of where wheel brands place these details, OZ Racing’s wheel marking page shows offset listed as ET and places it alongside width and bolt pattern. That makes it easier to spot the right number when a wheel has several codes stamped into it.

Where The Marking Usually Sits

• Back of the spokes
• Inner barrel near the bead seat
• Hub pad area
• Sticker on a boxed new wheel
• Retail spec sheet or maker catalog

Clean the wheel before you hunt for the code. Brake dust, old dressing, and road grime can hide a shallow stamp. A rag and mild cleaner are often enough. Skip aggressive scraping on painted or powder-coated wheels unless you are ready to refinish them.

What The Offset Number Tells You On The Car

Offset is all about the hub mounting pad and the wheel centerline. A positive number means the hub pad sits closer to the street side of the wheel. That pulls the wheel farther inward. A negative number means the hub pad sits closer to the suspension side. That pushes the wheel outward and gives the wheel a deeper dish look.

Zero offset means the hub pad sits right on the centerline. That style is common on older trucks, off-road setups, and some custom wheels. Most newer passenger cars use positive offset, often in the +35 to +55 mm range, though the exact figure depends on the car and wheel width.

Where You Check	What You May See	What It Means
Back of a spoke	ET35	Positive 35 mm offset
Inner barrel	18×8 ET45	18-inch wheel, 8-inch width, positive 45 mm offset
Hub pad area	+20	Positive 20 mm offset even if ET is not printed
Rear face of wheel	-12	Negative 12 mm offset
Retail box label	17×7.5 5×114.3 +38	Wheel size, bolt pattern, and positive 38 mm offset
Maker catalog	Offset range 38-48	That wheel style comes in several fitments
OEM parts listing	18×7.5J ET50	Factory size and offset for that trim
No visible marking	Measure it manually	Use width and backspacing to work out offset

Measuring Wheel Offset When The Stamp Is Missing

If the number is gone, you can still find wheel offset at home. Pull the wheel off the car, lay it face down on a flat surface, and grab a straightedge, tape measure, and notepad. This part goes smoother if the tire is off the wheel, but you can still get a good read with the tire mounted if your straightedge sits flat across the back lip.

Measure It In This Order

1. Measure the wheel’s full width from outer lip to outer lip.
2. Divide that number by two to find the centerline.
3. Lay the straightedge across the back of the wheel.
4. Measure from the hub mounting pad up to the straightedge.
5. Subtract the centerline from that backspacing figure.
6. Convert inches to millimeters by multiplying by 25.4.

Say the full wheel width is 9 inches, so the centerline is 4.5 inches. If backspacing measures 6 inches, the difference is 1.5 inches. Multiply 1.5 by 25.4 and you get 38.1 mm. That wheel is about +38 offset.

One snag trips people up: advertised wheel width is often measured at the bead seat, not lip to lip. That means a wheel sold as 8 inches wide may measure close to 9 inches across the outer lips. If you are measuring the wheel with a tape, use the real physical width you see in front of you. If you are working from a catalog width, check a fitment source first so your math does not drift by half an inch. Discount Tire’s offset and backspacing page lays out that lip-versus-width detail in a way that helps when you are doing the math by hand.

Once you have the number, compare it with the stock wheel offset for your car. A small change may fit fine. A larger jump can change inner clearance, poke, scrub, or steering feel. Offset never works alone. Width, tire size, suspension height, brake size, and fender room all join the math.

Positive, Zero, And Negative Offset In Plain Terms

Positive offset tucks the wheel inward. That is why you see it on many front-wheel-drive cars, crossovers, and newer sedans. Zero offset puts the mounting pad in the middle. Negative offset pushes the wheel outward and is common on deep-lip truck wheels and some off-road builds.

The number matters because two wheels can share the same diameter and width but sit in two different places on the car. A 17×8 +45 wheel and a 17×8 +20 wheel are both 17×8, yet the +20 wheel will sit 25 mm farther out. That can fill the fender better, but it can also rub the arch or throw road spray up the body side.

Go the other way and the wheel tucks inward. That may clear the fender, but it can get too close to the strut, spring perch, inner liner, or brake hardware. This is why wheel sellers ask for your exact year, make, model, trim, brake package, and suspension setup before they say a fit is clean.

Offset Change From Stock	Wheel Moves	What To Check
+5 mm more positive	Inward	Strut and inner liner clearance
+10 mm more positive	Farther inward	Brake and spring perch room
-5 mm less positive	Outward	Fender and arch clearance
-10 mm less positive	Farther outward	Poke, rub, and road spray
Zero to negative	Outward a lot	Wheel bearing load and full-lock rub

Checks That Save You From Buying The Wrong Wheel

Offset is only one line on the spec sheet, so write down the whole package before you order anything. That means wheel diameter, wheel width, bolt pattern, center bore, tire size, and your stock offset. Leaving out one of those numbers is how people end up with a wheel that bolts on but does not clear the brakes or sits wrong in the arch.

Write Down These Specs Before You Buy

• Stock wheel size and offset
• Bolt pattern
• Center bore
• Tire size now on the car
• Any spacer already fitted
• Ride height changes, if any
• Brake kit changes, if any

If you are buying used wheels, ask for a photo of the back of the wheel, not just the front face. That is where the useful numbers usually live. If the seller only sends glamour shots, ask again. A clear photo of the stamp can save a wasted trip, return shipping, and a set of tires mounted to the wrong rims.

So, how do you find the offset of a wheel without guesswork? Start with the stamp. If it is not there, measure the wheel and work the number out in millimeters. Then compare that figure with the stock spec for your car before you spend a cent. That small step keeps the wheel where it belongs: clear of the strut, inside the fender, and right for the way the car is meant to sit.