Towing and Overdrive

I'm new this message board. I didn't see any past threads on this.

At what towing weight do I need to turn off the overdrive? My rule of thumb in the past was if I noticed that it was shifting in and out of overdrive a lot, I would turn O/D off. Is this a good rule? I'm in the process of installing a transmission oil cooler. Does this allow me to use O/D since the temps should stay lower?

The only towing I do is an aluminum snowmobile trailer with one or two snowmobiles on it.

Heres the towing weight estimate:
Trailer and 1 snowmobile = 550 + 250 = 800 lbs
Trailer and 2 snowmobiles = 550 + 550 + 250 = 1050 lbs
Plus, two persons and their gear.

I will be towing from Minnesota to Montana later this month and would like to have the O/D on to keep the RPMs down while on the freeway at speeds of 70 to 75 mph.

The 4Runner is GREAT with towing. We had a 20 foot fishing boat behind our 98 Limited, and you could barely tell it was there. Plus we had 5 people + gear.

Id keep it in overdrive most of the time especially if its on flat roads. Climbing hills if its shifthing in and out id turn it off, but even then I find the 4Runner to be very well designed for this.

Your 4Runner should be able to tow your trailer with no problem. Take it out for a test run.