Tyre size V Diff ratio

Save your money, not worth the effort. Why do you want bigger tires? Ground clearance a problem for you?

in the case of a V8 yes, you will need to change, 3.9's are a good idea.

Roachie, happy to take the 4.3 R&P's off your hands. I'll even come over and pick them up. (Serious offer...)

Agree with Truckster about the Chev V8, not a revver but heaps of low down torque, will need the (numerically) lower ratio to keep the engine in it's torque band. Peak torque 3.0 about 2000 rpm vs Chev V8 about 1400-1800 rpm.

Here.
Do some number crunching

www.tyres1.com/calculators.html

I had 1999 GU patrol converted to 6.5 V8 Chev a few months back. It's fitted with 3.9 diffs and 275/75R16 tyres. In normal driving around town I use only 3 gears - second, third and fifth.

When towing a 2 tonne van, I use me all. Max torque is 1200 to 1400 rpm.

I tow at 85 to 100 kmh in fifth and it eats it. At 100 kmh, RPMs is 2000 ( I seem to remember that being correct - it's been sitting on the driveway all week!)

It will pull my 2 tonne van from a standing start using second gear with a bit of slipping of the clutch but that was only as an experiment.

If yer not gonna tow anything but a garden trailer with it, I reckon you could easily go 3.7 diffs for better economy. 3.7 diffs come from the 4.8 litre petrol Patrol.

The use of 3.5 diffs would be an interesting experiment ;) Do they make 3.5s ??

Bilbo