A wheel size looks like a password until you know where to break it up. Take 20x9 6x139.7 +18. That is four separate facts about one wheel.
20 is the diameter. The wheel is 20 inches across, measured at the bead seat, not at the outer lip. We build 20, 22 and 24 inch.
9 is the width. Nine inches between the bead seats. Most trucks take more than one width, and the wider one usually needs a different offset to sit right.
6x139.7 is the bolt pattern. Six studs, spaced around a circle 139.7 mm across. This one is not a preference. Your truck has one pattern and the wheel has to match it. The patterns we build are 5x114.3, 5x127, 6x135, 6x139.7 and 8x165.1.
+18 is the offset. The face of the wheel sits 18 mm outboard of the centre line. A higher number tucks the wheel further under the guard. A lower or negative number pushes it out. This is the number that decides whether the tyre rubs, and whether the wheel fills the arch the way you want.
One more thing lives with the size: the centre cap. Each bolt pattern has its own cap, so the cap part number changes with the size you pick. You can see it on every row of the fitment table.
Every Hartes Metal wheel is tested to 3,700 lb, whichever size you land on.
If your truck is not in the picker, send us the bolt pattern, the wheel size you run now and the tyre on it. We will check it by hand.
