What Is PCD in Alloy Wheels? PCD, Offset, Centre Bore and Bolt Pattern Explained
Quick Take
PCD (Pitch Circle Diameter) is the size of the imaginary circle that runs through the centre of every stud hole — written as holes x diameter, like 4x100 or 5x114.3. It has to match your car exactly, and so do three other things people skip: the offset (where the wheel sits in the arch), the centre bore (the hole in the middle), and the wheel nuts. Get the PCD wrong and you've bought a very expensive wall decoration. Get the other three wrong and you've bought a problem.
Here is the thing about alloy wheels. The design is what you fall for, but the fitment numbers are what decide whether the wheel ever goes on your car. And those numbers are printed in a code that rarely gets explained: 4x100, ET43, CB 67.1. To us it reads like a yes or a no.
This is for the person scrolling alloy listings at midnight, about to add a set to cart because it looks good in the photo. Give it five minutes first. We at TyresNmore would rather you understood these four checks than called us after the wheels arrive.
PCD and Bolt Pattern: Same Thing, Two Names
What Is PCD?
PCD stands for Pitch Circle Diameter. Draw an imaginary circle through the centre of each stud hole on your wheel. The diameter of that circle — usually given in millimetres — is the PCD. You will also see it called the "bolt pattern". It is always written as two numbers: the first is the number of studs, the second is the circle's diameter. So 4x100 means four studs on a 100 mm circle. 5x114.3 means five studs on a 114.3 mm circle — which looks oddly precise until you know it is exactly 4.5 inches wearing a metric label.
Three popular Indian cars show why this matters:
How to Measure PCD Yourself
On a four-stud wheel it is easy — measure from the centre of one stud hole to the centre of the hole directly opposite. That is your PCD. Five-stud wheels are trickier because no hole sits directly opposite another. The workaround is to measure between the centres of two neighbouring holes and divide by 0.5878. But a tape measure on a dusty wheel in a parking lot is a poor way to decide a ₹30,000 purchase. Your car's spec sheet, or a quick check with us, is the better route.
Offset (ET): Where the Wheel Sits in the Arch
What Is Offset?
Offset is the number people skip, and it is the one that decides whether the tyre rubs. It is the distance in millimetres between the wheel's mounting face (the flat bit that presses against your car's hub) and the wheel's centreline (an imaginary line down the middle of the rim's width). On listings and spec sheets it is usually written as ET followed by a number.
Tucks Into the Arch
The mounting face sits towards the outer, visible side. The wheel sits further inward, away from the arch edge. Common on most modern cars.
Perfectly Centred
The mounting face lines up exactly with the centreline of the rim. Uncommon on modern Indian passenger cars.
Pushes Outward
The mounting face sits towards the brake side. The wheel pushes outward, towards or past the edge of the body. Can cause rub and handling issues.
The second-generation Creta shows how offset changes with wheel size — even on the same car from the same manufacturer:
| Spec | Hyundai Creta (2nd gen) |
|---|---|
| PCD | 5x114.3 (five studs) |
| Centre bore | 67.1 mm |
| 16-inch wheel | ET43 — 6J x 16 rim |
| 17-inch wheel | ET49 — 6.5J x 17 rim |
Centre Bore: The Small Number That Causes Big Vibrations
What Is Centre Bore?
The centre bore is the hole machined in the middle of the wheel. On a hub-centric car, it slips over a raised collar on the hub — and that snug fit is what centres the wheel. The second-generation Creta's hub is listed at 67.1 mm; the 2011–2017 Swift at 54.1 mm. Mass-produced aftermarket alloys are often made with a centre bore large enough to fit the biggest hub they are designed for. On a car with a smaller hub, that leaves an air gap — and the wheel may not be perfectly centred.
That off-centre condition shows up as a vibration at highway speeds that feels exactly like bad wheel balancing. Rebalancing will not cure it, because the wheel is not out of balance. It is off-centre. The fix is a hub-centric ring — a precise spacer ring that fills the gap between the wheel's bore and your hub.
The Fourth Thing Nobody Mentions: Nut Seats and Threads
Your wheel nuts do not just clamp the wheel. The part of the nut that touches the wheel — called the seat — has a shape that must match the hole it sits in. A nut with the wrong seat touches only a thin ring of metal and can work loose while you drive. Reusing old nuts on new alloys is not automatically safe.
Conical Seat
A taper, usually 60 or 45 degrees. Used on most aftermarket alloys. The tapered end sits in a matching cone in the wheel.
Ball / Radius Seat
Rounded. Used on some OEM wheels, mostly certain European cars. Never mix ball-seat nuts with conical-seat wheels.
Flat Seat
Flat face with a separate washer. Used on some Japanese and commercial vehicles. Must match the wheel's hole design exactly.
All Four Checks Side by Side
| Term | What It Means | How It's Written | If It's Wrong | Can It Be Fixed? |
|---|---|---|---|---|
| PCD / Bolt Pattern | Circle through the stud holes | 4x100, 5x114.3 | Wheel won't seat on the hub | No. Choose a different wheel. |
| Offset (ET) | Mounting face to rim centreline | ET43, ET49 | Rubbing, poor handling, early wear | Pick a wheel with the right ET. |
| Centre Bore (CB) | Hole in the middle of the wheel | CB 67.1, CB 54.1 | Vibration that feels like imbalance | Yes, if bore is larger — hub-centric ring. |
| Nut Seat & Thread | Shape and thread of the wheel nut | Conical, ball, flat; M12 x 1.5 | Nuts can work loose | Yes — use nuts made for that wheel. |
What This Means When You Shop With Us
Many of our alloy listings show the stud count and PCD right in the product name, so you can rule out the impossible ones fast. On the 15-inch page, for example, you'll find 4-hole 100 PCD sets sitting next to 5-hole 114.3 PCD sets at nearly the same price — same size, completely different cars.
Why This Matters for Your Car
Alloys change how a car looks first, and how it drives second. But none of that benefit shows up if the wheel is not centred and sitting at the right offset. A slightly off-centre wheel on a Bengaluru flyover means a steering wheel that buzzes in your hands all the way home.
This is where how the wheels get fitted matters as much as which wheels you buy. TyresNmore offers doorstep fitment in Bangalore, Chennai, Delhi-NCT, Hyderabad, Mumbai and Pune, and our service vans carry wheel balancing equipment. In Bengaluru, our Experience Centre in Kasavanahalli also does wheel alignment and Road Force wheel balancing — which presses a roller against the spinning tyre to mimic the car's weight on the road, picking up a tyre that is not perfectly round or evenly stiff.
Related Reads
FAQs
What is PCD in alloy wheels?
PCD means Pitch Circle Diameter — the diameter of the imaginary circle through the centre of the wheel's stud holes. Written as studs x diameter in mm, for example 4x100. Your new alloys must have exactly the same PCD as your car's hub.
What is the PCD of the Maruti Swift?
Every Swift generation since 2005 is listed at 4x100. For the 2011 to 2017 model, spec databases also give a 54.1 mm centre bore and M12 x 1.25 threads. Confirm against your own car's documents or ask us before buying.
Is 4x100 the same as 4x108?
No. Both have four studs, but the circle is 100 mm on one and 108 mm on the other. A 4x100 wheel will not correctly fit a 4x108 hub, and it should not be forced on.
What does ET mean on an alloy wheel?
ET is the offset — in millimetres — between the wheel's mounting face and the centre of the rim's width. A higher positive number tucks the wheel further into the arch. The right ET depends on your car and on the wheel size you choose.
How do I find my car's wheel offset?
Check the markings on the back of your current wheel, the owner's manual, or a spec database for your exact model and year. Or send us your car model and variant and we will confirm it.
Do I need hub-centric rings for aftermarket alloys?
If the wheel's centre bore is larger than your car's hub, yes. The ring fills the gap so the wheel sits centred, which prevents a vibration that feels like poor balancing but will not be cured by rebalancing.
Can I use my old wheel nuts with new alloy wheels?
Only if the nut's seat shape (conical, ball or flat) and the thread size match the new wheel. A mismatched seat can let nuts work loose. When in doubt, use the nuts specified for the wheel.
What is the price of 15-inch alloy wheels at TyresNmore?
As of 21 October 2026, the 15-inch sets of four on TyresNmore ranged from ₹30,899 to ₹51,899, including taxes. Prices change — check the live listing.
Is PCD the same as bolt pattern?
Yes. Bolt pattern is just another name for the same measurement — both describe the number of studs and the diameter of the circle they sit on.
Final Word
PCD gets the wheel onto the car. Offset decides whether it clears the arch. Centre bore decides whether it runs true. And the nuts decide whether it stays on. Skip any one and the prettiest wheel on the page becomes a problem.
You do not have to memorise any of this. Just do not buy blind. Send TyresNmore your car model, pick the design you like, and let us do the fitment maths before the wheels ship.
