My old 31x11.50ss that i ran with the 970cc weighed pretty much the same as my 33x12.50s that I now run with the 1590cc, there is hardly any difference in size, I said "I have ONLY swapped from 31s to 33s" as in it's not a big change so should not have much of an effect on the fuel economy comparison between the two set ups I have run on MY sj
The twin transferboxes on mine makes a difference though with the extra transmission drag and weight. my 970cc was about the same on fuel with the 31s than my 100% standard 1.6 vitara was.
The best way to improve fuel consumption in an Sj is to run a more modern fuel injected engine, our 2.5 v6 is more economical than my Sj
