auto trans temps and big tires

'96, np231, 4.0, auto, stock

I am planning a small lift, 2-3", and would like to run 31" tires. I'll trim the fenders if necessary, and will probably be installing Rusty's high clearance trans crossmember to gain some more under body clearance. After this, new gears are at least a year away. New babies soak up wheeling money it seems

I know running oversize tires will increase my trans temps, but I am wondering if this is any worse than towing a trailer? Our XJ's have a pretty good tow rating, so shouldn't the AW4 stand up to the taller tires OK? Wouldn't a good aftermarket trans cooler take care of the problem? If the concern is that the lower engine RPM will result in lower fluid pressures, would a shift kit take care of this?

I know I am looking for band-aid solutions, but I also know there are lots of guys like me who can't afford a lift, tires, skids, and gears all in one shot. Somebody else must have thought about this before.

Thanks for any help.

Geoff Cameron

I don't think 31's will be that big of a deal...but you need a trans cooler at some point anyway for wheeling. The factory "tow package" setup works very nicely, and there are aftermarket alternatives as well.

Nay

I have a trans temp gauge, 33" tires with 3.55 gears, and no transmission cooler except for the one in the radiator. My transmission temp runs right around 200 when it gets warm. It gets hotter on the trails or if I leave it in OD, but my tires are way too big for the gears I'm running (going to 4.56 soon). You should not have any problems with 31s.

I ran 30s and 3:55s with a medium duty trans cooler for a year with no problems at all. I really noticed it when i went up to 33s. Luckily, I've only ran those for about 2 months, and it's in the shop getting regeared as I type. (and ARBs and a Ford 8.8, but who's counting?) btw, 98/auto/231