if you dont have transfer gearing there are no pros

i mean it will be such a pig to drive both on and off road that you will wish you hadnt bothered

Engine conversion, or some performance work on your existing setup (assuming you haven't done any already).

g16b vitara engine

It's tuesday

more power doesn't offset taller tyres. More torque lower in the rev range will help, but some quick and rough maths tells me a coiler on 31's would be spinning at about 2800rpm @ 100km/h with 31's on it, so you'd need an engine that puts out 20% more torque than a G13B at 3500rpm whilst spinning at 2800 rpm. That's beyond even a G16B. Gearing really is the better option.

OK, you need to fit a Leaf sierra transfer case to you coil car. From memory, this will require a WT jackshaft as well as the coil jackshaft is longer. It will be best to find a WT transfer case as it will have the right flange bolt pattern. You can then fit low range transfer gears which will almost correct the road gearing and will bring offroad awesomeness.

Once you've done this (and this is a circa $1K exercise unless you find a transfer with gears cheap) you might find the coil front CV's and inner axles are a weak link. There's no commercially available fix for this problem, although custom axles and using the stubs from doubletoughs are possible, similar to what 31zook has done for his jimny.

If you are a sympathetic driver and drive mostly mud you might find the front end lives, but it's always going to be borderline.

Likewise if you are into mud mostly, you might *just* get away with a 1.0 "switch light* transfer case, but it's going to be less than ideal and it requires the flanges swapped to WT items to match your driveshafts.

if this all seems like a lot of money/work unfortunately that's just the nature of things. a 31" tyre is 20% increasem that's like putting a 38" tyre on a patrol - it costs money to get the car right with that much tyre.

Steve.

31s are about 7% larger, depending on brand.

It doens't matter if it's an AT, a MT or a slick - it's the gearing, not the tread pattern that matters.

You can check transfer gearing by jacking the back wheels up, turning the driveshafts, and counting out the ratios. I'd say your car would already be pretty horrible to drive with 235's and stock gearing, the added weight and height of 31's will really make it suck. I' already have changed the gearing if I had a coiler and was running 235's.

Steve.

Yes, but you need to do it with the transfer case.

Put the transfer case in low range, gearbox in neutral, and with the back wheels off the ground, turn the tailshaft once and count how many times the jackshaft turns. The jackshaft is the little shaft between the gearbox and the transfer case. If it's roughly 2 times, everything is standard.

If it's just over 2.5 times, you have a 1.0 transfer case.


Steve.

so no point in getting 31s then ?

You don't have to do an engine swap or get reduction gears! I ran 31x10.5 muddies on my sierra with stock engine and transfer and it ran fine!! It was a bit slower but it was still good off road and on road!! I only did the engine swap because I flooded my ok engine...