FJ40 tyre choice for cape york,31s or 33s?
planning a cape york trip in the dry season. the fj40 is on stock suspension with the disc brake conversion done. currently running 235/75r15 which are about 29 inches. thinking of going up to 31s or 33s for the extra clearance but dont want to regear the diffs if i can avoid it. whats the sweet spot for a stock-ish 40 series on cape tracks?
31s are the sweet spot on stock gearing. 33s will make the 2F engine feel gutless on hills without regearing. the 4.11 factory ratio with 31-inch tyres gives you similar rpm to stock on the highway. i run 31x10.5r15 cooper ST maxx on my xc70 for fraser island and they clear everything fine. for cape york you want all-terrain not mud terrain, the corrugations will shake your fillings out with MTs.
We met several Land Cruiser 40s on the Cape York trip last year and the ones on 31s seemed to handle the tracks much better than the ones on big mud tyres. The corrugated sections are the real challenge up there, not the river crossings. Comfort and reliability matter more than ground clearance for a trip that long.
cant comment on cape york but ive seen fj40s struggle with 33s and stock gearing on steep fire trails near lithgow. the engine just cant pull them without the rpm dropping into nothing. 31s keep you in the power band. if you ever do regear a 4.56 ratio with 33s is the go.