LC HZJ78 2001 5th gear ratio change

[Gap]

Hi LCC forumers, I have a question regarding 5th gear ratio change with which googling didn't help.

My 2001 LC HZJ78 with a 4.2 inline-6 diesel makes driving open roads (especially highways) with more than 90 km/h (55 mph) uncomfortable. With the engine being generally underpowered, the gear ratios are a major issue for high RPM.

I was looking for adapted gear ratio wheel, such as the one below, however, this one is for newer 4.5 L models:
https://www.allfourx4.com.au/5th-Ge...iser-HDJ-VDJ-76-78-79-33421-60121-33036-60010

Do any of you happen to know whether there are any adapted gear ratio wheels out there for the old 4.2 versions? Any other solutions to high RPM on open roads, other than being patient and driving slowly?

 

[TheoM]

What size tyres are you running ? Do you have stock diff ratios ?

 

[Gap]

The tyres are 235/75 R15 BFG All-Terrain KO2. Some 20 % larger in perimeter and width than the originals. You can feel this when starting in 1st gear (somewhat "harder" kick-off), but I'd think for driving at speed it should be easier, i.e. less RPM.

And stock ratios, indeed.

 

[TheoM]

I think your tyres are too small.Should you not be on 16" rims to begin with ? Around here guys have used 235x 85 R16 or even 255x85 R16, if turboed.