3rd Gen Towing in D or S for hills???

I cant find much information on 3rd Gen towing techniques. Owners manual doesnt have much unless I missed it.

I have a 2024 Limited Tundra. I'm towing a 5,000lb trailer and gear through the Rocky Mountains with some pretty serious uphill/down sections. I'm most worried about the long downhill sections. It will be 10,000ft of climbing then 10,000ft of descending in a 2 hour window.

Older gen tundras with 6 gear transmission said to go into S mode and stick to gear 3 or 4 to help engine brake down the hill.

What do we do in our 3rd Gens?? S Mode and stick to gear 7 or below? I suppose I'll just keep downshifting until the RPM's feel right - but any feedback would be great.

 

Update- so after towing on these ‘hilly’ highway roads I learned S mode is very necessary to not destroy the brakes.
When you kick into S mode it starts in 6th gear. That only works on slight hills. Any hill grade 6% or higher I had to use 5th or 4th gear. A couple 12% grades I had to use 3rd gear and go real slow and still ride the brakes.
So even though this is a 10 speed tranny - you’re still mostly using gears 4/5 for downhill towing in my experience.

 

Did you notice any changes in transmission temperature? What RPM were you pushing it to

 

On the downhill no change in temperature. I would adjust my speed to not let it go over 4,500rpm. I found 4,000rpm was a sweet spot for helping slowdown the truck/trailer.
My oil temp got pretty high on a climb out of Vernon towards Merrit. I think it’s about a 1,600 meter (4,500ft climb) while driving straight up hill for 30 minutes or so.
I might hook up my Veepeak obd2 connector next time to get actual numbers instead of just using tundra tow gauges.

 

Right on I’ve also been towing a 5000lbs camper, gear and family. Nothing through the mountains yet other than just to Nordegg and north around Whitecourt. So
Thanks for sharing

 

Try the Tow+ or Tow+Haul mode. Press the Tow Mode Button and then turn the selection knob. These modes automatically lock out upper gear ranges, alter the shifting patterns, modify the AFR and Turbo. No need to use the S mode for towing if you use either of these options.

 

maybe for going up the hills and towing in general. But down shifting manually to let the engine and transmission do some of the work braking would require being in S mode. The hills I’ve come down Tow haul won’t down shift for that

 

my engine braking works fine in the Tow+ and Tow-Haul mode. No upshift - speed held and rpm goes up, but yes, I still have to use the brake to reduce the speed. Some significant grades here where I am at in Colorado. I used S mode on my Tacoma and yes it works like you say.

 

Thanks for the tip. I actually always tow in Tow+ mode. Owners manual says it’s meant for 5,000lbs plus. I’m right on that border so I always used it. In all my towing experiences it hasn’t done a thing to help downhill engine braking.
If youre going heavy on the brakes is it actually downshifting to help slow you down??

 

when doing down grade mine simply does not allow for an upshift - thus holding the current gear which results in rpm reaching 4 krpm. Use of the brake is the only way to actually make it slow down. You could use the S mode - like @NORTHof54 does to actually downshift and not rely on engine-braking to hold your speed from increasing. I'd say each incident has to be evaluated on the fly. I really liked S mode in my Tacoma - but that was also the Tow Mode and I used it 100% of the time when towing per the Owners Manual. I use Tow+ or Tow/Haul mode 100% of the time when towing with my Tundra - I'd like to know what Toyota's official word is on using S mode for downshifting to slow speed when towing.

 

I found the engine braking in the Tow Haul mode works great on a 10% grade. I was surprised the first time it came on and our trailer weighs 4,100 lbs. Didn't touch the brakes all the way down the hill and kept the speed constant. Pretty happy with that. I left the shifter in "D" throughout.

 

Have you done the Merritt to Hope drive? That’s a tough one on brakes. I guess there’s a reason there’s so many runaway truck ramps that clearly get used.

 

We have done that many times. There is the steepest section at the snow sheds that is pretty brutal. That one requires that you stay on the brakes because of the curve at the bottom. My wife freaks out if we are moving too quick on that section!

We have driven that road with both of our trailers over the years but not with the Tundra. Just haven’t travelled that way in the last couple of years and then the recent recall prevented us from taking the Tundra to Jasper and Edmonton. We used a buddies Taco for that trip.