Hi Hal9000 , mate I use 245/75/16 and thought at first it would sap the little power remaining however this is not the case.lol... yea.. I recon hah.. just noticed..
The reason is simple-- the car weights 1800Kg without me in it. It has 5.1:1 Diff ratio. The issue of slack acceleration on 2wd High is simply the weight more so than the gearing. Add in some wind resistance and you get the picture.
Now I was skeptical on this subject but worked out that going to 245 /75 was going to be almost undetectable in terms of overall gearing when the weight is more the issue for a 2.0 to get going.
So I found the 245/75 is a great tyre combo-- its narrow enough to bite, doesn't drag too much in the sand reserving the 2.0 power to keep pushing forward and not stall. The 75 Ratio means you can let alot of air out the tyre and get good traction.
Little greenie has conquered all of the Bendleby Ranges in Southern Flinders as pictured above in this blog and is a hell of a-lot of fun in the process.