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Gear ratio
Posted: Tue Dec 07, 2010 2:18 pm
by Cobvs
Picked up this thread
https://www.4x4community.co.za/forum/sh ... hp?t=71763
and I am interested to know if the Gen 2's came out with 31x9.5x15's? Also what exactly is done when changing gear ratio to adapt to bigger wheel size? How do you determine the new gear ratio?

Re: Gear ratio
Posted: Tue Dec 07, 2010 2:41 pm
by SimonB
No need to stress out about gear ratio's on the Gen2. They run 31x10.5/15 just fine. I believe the "standard" was 265/70R15 (Gerrit will know) which is a smidgen smaller.
Re: Gear ratio
Posted: Tue Dec 07, 2010 6:09 pm
by tonton
SimonB wrote:No need to stress out about gear ratio's on the Gen2. They run 31x10.5/15 just fine. I believe the "standard" was 265/70R15 (Gerrit will know) which is a smidgen smaller.
I agree. I run on 31x10.5/15's, and my gear changes are quite in line with those proposed in the manual.
If anything, I have a slightly more accurate odo, and better fuel consumption on the open road.
I do not agree (as claimed on the referred post in 4x4Community) that bigger tyres improve crawling, though. Surely bigger tyres cover more distance per turn of the wheel?
Anton
Re: Gear ratio
Posted: Wed Dec 08, 2010 7:28 am
by Gerrit Loubser
The 3.5 V6 Gen 2s came standard with 265/75R15 tyres, if I recall correctly. Those tyres have a nominal overall diameter of 30.65", so the 31x10.5R15 tyres would be almost identical in diameter to OEM.
Fitting larger diameter tyres will result in reduced tractive effort and engine braking, which could hamper crawling performance, but on the other hand, the larger tyres roll over obstacles more easily and increase ground clearance, both of which help the vehicle in the rough stuff.
Re: Gear ratio
Posted: Wed Dec 08, 2010 1:46 pm
by Cobvs
Gen 2. 3.5 has increased power over the Gen 2 3.0 so I can understand that the 3.5 do not have issues running with 31's. The 3.0 however is a bit pap and needs more oemff. Therefore running the 31's on a 3.0 is a bit of a backdraw but I still like to stability of a broader tyre. therefore my question regarding changing the gear ratio to maybe get a bit more oemff even though you might lose top end.
