The Short Version
- 6×139.7, six studs, on every Bighorn grade the Japanese factory tables actually contain.
- The Japanese tables do not publish a hub bore for this vehicle at all. Not for the first generation, not for the second. The field is empty on every grade.
- Coverage stops in October 1992. The bulk of the second-generation run, 1993 to 2002, is simply not in the database.
- So this is a shorter guide than usual, and deliberately so. We would rather tell you where the data ends than fill the gap with something we cannot stand behind.
What Is Actually Confirmed
| Period | Grade | Chassis | Wheel | Bolt pattern | Bore |
|---|---|---|---|---|---|
| 1990.06–1992.02 | 4WD 5-door Irmscher S (Long) 4AT | Q-UBS55 | 6J×16 +30 | 6×139.7 | not published |
| 1992.02–1992.10 | 4WD 5-door Long Handling by Lotus 5MT / 4AT | Q-UBS69GWS | 7J×16 +38 | 6×139.7 | not published |
| 1992.02–1992.10 | 4WD 5-door Long Handling by Lotus 4AT | E-UBS25GWS | 7J×16 +38 | 6×139.7 | not published |
Note the offset step: the late first-generation Irmscher cars sit at +30 on a 6J rim, and the early second-generation Handling by Lotus cars at +38 on a 7J. Half an inch wider and eight millimetres further in. If you are buying used wheels described only as “Bighorn”, that is a visible difference at the arch.
Why You Should Measure the Hub Yourself
On a two-tonne body-on-frame vehicle, the hub register is structural. The studs clamp the wheel to the hub face; the register is what centres it and carries load. Fitting a 6×139.7 wheel with the wrong bore — too large, so it is centred only by the taper of the nuts — is a real problem on a Bighorn in a way it would not be on a light car.
Since we cannot give you the number, here is how to get it. Take the wheel off. Measure the diameter of the machined circular step the wheel seats on — the raised centre boss, not the outer edge of the hub flange, and not the hole in your existing wheel if that wheel is aftermarket. Measure it in two directions and take the larger figure. That is the number a hub-centric ring must match.
Send us the figure with your chassis code and we will match wheels to it. We will also add it to this guide, credited, because the Japanese databases evidently are not going to.
A Note on the Source Itself
While pulling this data we found that the Japanese wheel database files the Isuzu Bighorn under Subaru in its manufacturer taxonomy. The chassis codes on the page — UBS55, UBS69, UBS25 — are unambiguously Isuzu, and the grade names are Isuzu’s own, so this is a data-entry error on their end rather than any relationship between the two companies.
We mention it because if you go looking for the source yourself, you will not find the Bighorn where you expect it. It is a small thing, but it is the kind of small thing that makes people give up on a search and then buy from a listing instead of from a spec sheet.
The Badge-Engineered Relatives
The Bighorn was sold under several names: Isuzu Trooper in the United States and Europe, Acura SLX, Honda Horizon in Japan, Opel Monterey and Vauxhall Monterey in Europe, and Holden Jackaroo in Australia. All are the same UBS platform.
We did not independently verify the wheel specification of any of them against a primary source, so we are not going to assert that they are identical. What we can say is that they are the same vehicle underneath, which makes shared fitment very likely and makes the used-wheel pool much larger than “Bighorn” suggests. If you own a Jackaroo or a Monterey, measure and tell us; we will check against Bighorn wheels before you buy.
Importing
Isuzu sold the Trooper new in the United States through both generations, so US-market cars are already local and parts support exists. For a JDM Bighorn, both generations are past the 25-year mark in full — production ended in 2002 and the final cars cleared in 2027 at the latest, with everything up to August 2001 eligible now.
What We Could Not Verify
- Hub bore, for any generation. The field is empty on every grade in the Japanese database. We found no manufacturer figure.
- 1993 to 2002. The database returned nothing for the bulk of the second-generation UBS69 and UBS73 run. Secondary databases list 6×139.7 continuing throughout, which is consistent, but we did not confirm it from a Japanese primary table.
- Wheel specifications for the Acura SLX, Honda Horizon, Opel and Vauxhall Monterey and Holden Jackaroo.
- First-generation data before November 1988.
Seen on the road
Which wheels are you looking for? Tell us the wheel, the size and the fitment — send us a request and we will go and find it.
Wheel identification is taken from the hashtags the owner applied to their own post.