The Holden Torana GTR XU-1 is a piece of Australian automotive history. Get the offset wrong on a car worth $50,000+, and the damage is real, fast, and expensive.

The Holden Torana GTR XU-1 (LC/LJ, 1970–1974) runs a bolt pattern of 4×101.6mm, a stock wheel size of 6J×14, and a factory offset of approximately ET+0 to ET+10¹. The hub bore is 82.6mm². These are not estimates — these are the numbers you need to build a wheel that actually fits.

Every owner who searches for wheel specs on a Torana GTR XU-1 has already done the hard part — they found the car, they’re committed to the build, and they have real money on the line. What they need now is a supplier who knows these numbers without being told. We do. And in this article, I’ll walk through everything you need to know about fitting wheels correctly on one of Australia’s most iconic classic cars.

What Wheel Offset Does the Holden Torana GTR XU-1 Actually Need?

Most people assume Australian classics use standard metric bolt patterns. They don’t. The Torana GTR XU-1 uses an imperial-derived PCD that locks it out of nearly every modern aftermarket catalog — and that’s a problem most suppliers won’t tell you upfront.

The LC/LJ Torana GTR XU-1 needs a 4×101.6mm bolt pattern, a hub bore of 82.6mm, and an offset between ET+0 and ET+10. Stock wheels were 6J×14³. This PCD is rarely stocked by mainstream suppliers, which makes custom forged wheels one of the most practical solutions available.

A customer contacted us not long ago — he had spent six weeks searching for a set of 14-inch wheels for his LJ Torana restoration. Every supplier came back with the same answer: \"We don’t carry 4×101.6.\" He was about to give up and use adapters. We told him not to. We asked him to send us his measurements, and we built the wheels from scratch. That story is not unusual. In fact, it is exactly the situation that a custom forged wheel manufacturer is built to solve, because we start from a blank sheet, not a catalog page.

Why 4×101.6mm Is So Difficult to Source

The 4×101.6mm PCD is a legacy imperial measurement from the early Holden era⁴. Almost no modern wheel brand produces molds or tooling for this pattern. Here is a quick breakdown of how it compares to more common patterns:

The gap between 4×100mm and 4×101.6mm is only 1.6mm per side. That sounds small. But bolt holes do not flex — that 1.6mm difference means a 4×100mm wheel physically cannot be centered correctly on a Torana hub⁵. Some people force it. The results are not good. When we produce a wheel for the Torana, the PCD is drilled to 4×101.6mm exactly. Not approximate. Not adapted. Exact.

What Happens If You Use the Wrong Offset on a Torana GTR XU-1?

Offset errors are measured in millimeters. The damage they cause is measured in dollars and months. On a 50-year-old car with a restored interior, a repainted body, and rebuilt suspension, a wrong offset is not a minor inconvenience — it is a serious and expensive mistake.

On the Holden Torana GTR XU-1, an offset error of just 15mm in either direction causes wheel rubbing, bearing stress, or illegal protrusion⁶. The scrub radius also shifts, which changes how the car behaves under braking. On a car with 50-year-old steering geometry, even 10mm matters.

I spoke with a shop owner in Melbourne who installed a set of aftermarket wheels on a Torana build. The PCD was close enough with an adapter, and the offset was ET+25 instead of ET+8. The wheels looked fine in the driveway. The first time the owner took a corner at speed, the front left wheel was rubbing the inner guard. The wheel was scratched. The guard needed repair. The adapters came off permanently. Total damage: around $1,400 and three weeks of rework. The point is not to scare anyone. The point is that offset is not a \"close enough\" number. It is an exact one.

Offset Error Consequences at a Glance

Beyond the physical damage, there is a handling issue that many owners overlook. The scrub radius — the distance between the steering axis and the wheel centerline at ground level — changes when offset changes⁷. On a car with original 1970s steering geometry, even a 10mm shift in scrub radius changes how the front wheels track under braking. Owners who have experienced this describe the car as feeling \"nervous\" or \"wanting to pull.\" That is not a comfort issue. That is physics. And on a car that may already be running period-correct drum brakes or early disc setups, unpredictable handling is a genuine safety concern.

Can You Run a Custom Forged Wheel on a Holden Torana GTR XU-1?

Because the Torana GTR XU-1 uses 4×101.6mm, most owners are left with three real options: hunt for original used wheels, use adapters, or order custom forged wheels built to exact spec. Two of those options carry serious risks. One does not.

Custom forged wheels built to 4×101.6mm, ET+0 to ET+10, and 82.6mm hub bore are the most reliable fitment solution for the Holden Torana GTR XU-1. Our MOQ is 4 wheels — one car. We produce 3D models before production begins so you can confirm the look and fitment before any metal is cut.

When a customer tells me they want to keep the car looking period-correct but original wheels are nowhere to be found, I always suggest going custom forged. We can replicate a Minilite-style spoke pattern in 14 inches, build it to 4×101.6mm with ET+8, and deliver in 15 to 20 days for a one-piece forged wheel. The owner gets a wheel that looks right, fits right, and weighs less than the original cast wheel. That is not a compromise. That is an upgrade.

Comparing Your Real Options for Torana GTR XU-1 Wheels

We also offer 3D models and design sketches before production starts. The owner sees exactly what the wheel looks like — spoke count, dish depth, lip width, finish — before a single piece of metal is touched. This matters a lot when the car is a concours-level restoration and the owner has already spent $60,000 on bodywork and paint. No one wants a surprise at the end of the build. We do not let that happen.

How Do You Measure Wheel Offset on a Holden Torana GTR XU-1?

If you are ordering custom wheels, your supplier will ask for your offset measurement. Do not guess. Do not look it up on a forum and hope the answer is right for your specific wheels. Measure it yourself — it takes less than 15 minutes and the process is straightforward.

To measure offset on a Torana GTR XU-1: remove the wheel, measure total barrel width (approximately 152mm for a stock 6J×14), divide by two to find the centerline (76mm), then measure from the mounting face to the back edge. Subtract the centerline from that number. The result is your ET value.

Every custom order we receive starts with the same form — PCD, offset, hub bore, width, and diameter. It takes the customer about 10 minutes to fill out. But those 10 minutes are what separate a wheel that fits perfectly from one that has to be returned or remade. I would rather spend 10 minutes on measurements than three weeks fixing a mistake.

Step-by-Step Offset Measurement for the Torana GTR XU-1

Follow these steps using a standard steel ruler and a pair of calipers.

A few things to keep in mind after you have your numbers. If your new wheel has a hub bore larger than 82.6mm, you will need hub centric rings to center the wheel correctly on the hub. If the bore is smaller, the wheel will not physically mount. This is a detail some suppliers skip over — we do not. Hub centricity is part of what prevents vibration at speed and reduces stress on the wheel studs⁸. On a classic car that may already be running at the edge of its original specifications, getting this detail right is not optional.

Conclusion

The Holden Torana GTR XU-1 needs exact numbers — 4×101.6mm, ET+0 to ET+10, 82.6mm hub bore. Get them right, and the car drives as it should. Get them wrong, and the cost is real. At Tree Wheels, we build custom forged wheels to your exact specifications — one car at a time, with no guessing.