Owners asking what wheels fit a Dominator or an HQ get the same unhelpful answer as owners asking about bearings: check yours. That is correct, and it is also useless unless you know how.
This guide is the how. Ten minutes with a tape measure gives you every number you need to buy a spare, a replacement or an upgrade that actually fits, and it works regardless of model year or whether an axle has been changed.
Why you should measure rather than look it up
Two reasons, and they both apply to campers like these.
Specifications change. Axle and wheel fitment has varied across model years and across the range, and a camper that has had an axle replaced may match nothing published. A table for "the HQ19" describes one build, not necessarily yours.
The cost of being wrong is high. A wheel with the wrong bolt pattern does not go on. A wheel with the right pattern but the wrong centre bore or offset goes on, and then fouls the suspension, rubs the body, or loads the bearings unevenly. Some of those show up on the first corrugated track rather than in the driveway.
Measuring the wheel in front of you removes both problems.
The five numbers
A wheel is specified by five things. You need all of them to match, not just the first.
| Number | What it is | Why it matters |
|---|---|---|
| Bolt pattern (PCD) | Number of studs and the diameter of the circle they sit on | Wrong pattern will not go on at all |
| Centre bore | The hole in the middle of the wheel | Must fit over the hub, and ideally locate on it |
| Offset | How far the mounting face sits from the wheel's centreline | Decides whether it fouls the suspension or the body |
| Rim diameter and width | The size the tyre fits | Must suit both the tyre and the wheel arch |
| Load rating | The weight each wheel is rated to carry | Off-road campers are heavy and the loads are dynamic |
Measuring the bolt pattern
Count the studs first. Trailer wheels are commonly five or six stud. Then measure the circle.
Five stud, which is the awkward one. You cannot measure across the circle directly because no two studs are opposite each other. Measure from the centre of one stud to the far edge of the stud two positions away, then read that against a pattern chart. A quicker method that works well enough for confirmation: measure from the back edge of one stud to the centre of the nearest non-adjacent stud.
Six stud is easy. Measure centre to centre across the wheel between two directly opposite studs. That is the PCD.
Measure in millimetres and in inches and write both down, because wheels are sold in both. Common six-stud trailer patterns include ones described as 6 on 5.5 inch, which is 6 x 139.7 mm, but do not assume yours is that just because it is common. Measure it.
Check the stud size too. Note the thread on the studs and the seat of the nut, which is either tapered or flat with a washer. Wheels are made for one or the other and the nut for the wrong seat will not clamp correctly.
Measuring the centre bore
Take the wheel off. Measure the hole in the middle with a vernier or a tape. Then measure the diameter of the hub it sits over.
If the wheel's bore matches the hub closely, the wheel is hub-centric: the hub locates it and the studs just clamp. If the bore is bigger than the hub, the wheel is lug-centric: the nuts locate it. Either is fine if the wheel was designed that way, but a replacement wheel with a bore smaller than the hub will not go on, and one much larger than the hub on a hub-centric design can sit off-centre.
Measuring offset
Lay the wheel face down on a flat floor. Measure the total width of the rim, edge to edge, and halve it: that is the centreline. Now measure from the floor up to the mounting face, the flat surface that sits against the hub.
- Mounting face at the centreline: zero offset.
- Mounting face further out, toward the road: positive offset, the wheel tucks in.
- Mounting face further in, toward the trailer: negative offset, the wheel pushes out.
Off-road campers often run some negative offset to push the wheel out for clearance. Matching what you have is safe. Changing it moves the tyre relative to the suspension arm and the body, and on an independent suspension a wheel that has moved inward can foul the arm at full compression.
Rim size and width
Both are usually stamped on the inside of the rim, typically as diameter x width, for example 16 x 7. If the stamping is unreadable, diameter is the tyre bead seat measurement and width is the inside bead-to-bead measurement, not the outside edge to edge.
Read the tyre sidewall for the size and the load index while you are there. The tyre tells you what rim width it wants, and our off-road trailer tyre buying guide covers matching the two.
Load rating
Every wheel has a maximum load stamped on it. For a camper with a gross weight in the region these run, and the dynamic loads of off-road towing on top, the wheel's rating divided by the number of wheels needs a healthy margin over the loaded axle weight.
Do not put a light-duty trailer wheel on a heavy off-road camper because the pattern happened to match. It will match. It will also fail.
Buying a spare
A spare should be the same as the wheels on the ground: same pattern, bore, offset, size and rating. A spare that differs in offset or size is a wheel you can limp on, not one you can keep towing on, and on a long track that distinction matters.
Once you have the numbers, a folding spare bracket on a square bumper, or a universal three-nut mount that suits most four, five and six stud patterns, gets it carried. Check the mount's rated load against the weight of your wheel and tyre together.
Write it down
Put the five numbers on a card in the glovebox and in your phone. The next time a tyre shop asks, or you are ordering a wheel from the side of a track, you will have them.
And while the wheels are off, the hubs are exposed: it is the cheapest time to check the bearings. Our bearing sizes and repack guide covers identifying your set, and we stock the 10-inch and 12-inch Timken kits.
Send us your five numbers and your model and we will tell you what fits before you order a wheel. Everything ships from Upland, California.