31" tyres on a Gen 4

Lambert wrote:

I'm finding your experience very interesting. Notwithstanding clearance issues you are saying that the automatic gearbox actually responds better to bigger tyres than intuition would suggest? Do you happen to regularly monitor transmission temperature and if so how is that affected? Also when you mention acceleration have you been able to independently quantify the difference or is it just more of a seat of the pants feeling of being slower?

I haven't monitored the transmission temperature, I must do so and see what the difference is from before. 

Acceleration wise there is a marked difference, by the seat of my pants, not something that I have ever thought to measure.

300bhpton wrote:

Lambert wrote:

I'm finding your experience very interesting. Notwithstanding clearance issues you are saying that the automatic gearbox actually responds better to bigger tyres than intuition would suggest? Do you happen to regularly monitor transmission temperature and if so how is that affected? Also when you mention acceleration have you been able to independently quantify the difference or is it just more of a seat of the pants feeling of being slower?

For low speed the auto box, well the torque converter will often compensate very well and you can always ride the brakes to go slower.

Trans temps are a good thing to consider, but no built in gauge on the Jimny unless it is available via the OBDII? I would think heavy technical off road, heavy towing or using in hot climates would be the main concerns here. Normal UK weather and mild off roading and short distance towing less of an issue.

I've seen vids of people with 235/75R15's on and the auto and acceleration times looked glacial. Maybe in the 18 sec region, with 31's and the same gearing I guess a juiced JBC Fastrac would give you a good run for your money....  
 

I have an OBDII reader using SZ Viewer, which gives transmission temperature. 

I'm planning to do a trip on the Easter weekend. The trip is a high mountain very rough trail over 2 days, which is continual difficult obstacles - Baboon's pass, Lesotho.
The first time I did it I had just fitted the 235's and I had the stock gearing, and didn't experience any issues. 
With the low range gearing reduction of 85%, I doubt I will have any issues with the bigger tyres.

Some feedback after about 8 months.

The tyres are great on-road. Lots quieter than the M/T's and they actually have decent road holding.

Off-road, they rubbed on all for corners at the top of the arches, but I was able to conquer an obstacle that I couldn't do before the bigger tyres.  That left me with a few options, I could just fit extended bump stops, a body lift or I could lift the suspension by another 25mm.

I opted for the 25mm lift. Des Sol, a local company that I have sourced most of my goodies, including the 50mm remote reservoir mono-tube shocks, was able to supply me with the parts I needed. They extended my shocks to 75mm and supplied extended bump stops, spring spacers, prop spacers and a new cross member.

I still need to test it off-road with the new lift. 

Impressive. What's that then like about 450 to 500mm under one tyre with the other 3 on the floor?

That's some serious articulation!