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I believe it's more about the diameter of the tire than the weight.
.You quickly get into the weeds with this. It really depends on the engine torque band and where your new tires put it. For example, stock form in 6th gear at 75 mph we sit around 1900rpm and if you jump up to a 33" that brings it down to 1750rpm. Doesn't seem like much but then look at that area of the engine torque. 30.5" = 140ft lbs, 33" = 130ft lbs. Add your driveline losses, added vehicle weight, aero and it ends up making a difference. The upside for us is the V8 masks a lot of that. In my last V6 mid size the difference was more like 30ft lbs, so the need to re gear was much higher. It also helps having a 3.909 axle ratio stock too. Personally I don't see the need unless you're running 33" Metric Load or 34"+ any load. You won't see a huge gain until you have enough tire weight or large enough tires. The vehicle weight won't make a huge difference unless you are overloading it regularly.
It does make a big difference towing. I'm in a 470 with slightly different gears but the 3.73/A750F combo makes it very difficult to tow our camper at 65 mph (ideal speed for traffic/safety/getting somewhere). In 5th gear this is something like 1,800 rpm which is too far down the torque curve and won't work on anything but flat ground. In 4th gear it's something like 2,700 rpm and pulls great, but gets crappy fuel economy. 2,200-2,300 rpm would be perfect, which I should be able to get with 4.56's and 33s. The alternative is to pull it at 70+ mph and get into that torque curve, but that also kills fuel economy and is faster than I want to tow for safety reasons on most roads.
Has not been a problem at all with my Wildpeaks. They are on the "heavier" side of the P-rated AT tires. We have lots of sharp chert and volcanic rocks around here as which are silica-rich, very hard, and great at slicing tires. But these Wildpeaks handle it fine. I wouldn't run the Rubicon on P-rated tires but they've far exceeded my expectations. I have 40K on them now, they'll get replaced next year at 45-50K as I like a little deeper tread, but I think they'd make it to 55K no problem.
Yeah, but you only have 5 gears
and if you don't have VVTi you are also even lower. Probably closer to a modern V6 than a V8 in power band. But either way there are two ways to solve it: Increase your low end torque or increase the RPM.I have VVTI, long-tube headers, custom catback exhaust, CAI, and a tune. It runs waaaaay better than it did stock. I am betting my 2UZ is putting out as much horsepower as a stock 1UR with a fair amount more torque given the engines were only 9 ft/lbs apart stock-to-stock and how significant the power differences were with my mods. But it still does not make enough power to tow a 4,000# camper comfortable at 1,800 rpm.Yeah, but you only have 5 gears
Ha-ha-ha!! You'll be getting rid of your Wildpeaks when they're about their lightest weight being worn down!! LOL!
On the 255/80/17 no regear. I find my foot to be much more smoother than cruise control. So far I have added a front bumper, winch and rear bumper. My combined weight up front is ~110lbs and the rear is ~50lbs. (Third row and oem tow hitch removed). I still have to add in the budbuilt skids which will add 190lbs.
Ours is a low-profile collapsible and not really any higher than the GX. A 5K loaded normal camper would definitely be a bigger effort to tow! I can get 13-14 mpg towing ours on 2-lane backroads when I'm averaging 55 mpg or so and taking it easy. On the interstate it's more like 11.5 mpg.
My point was making sure to use ATRAC and have your center diff locked and you should be good.
Yup, I'm always struggling whether or not to air down for how long I'll be on a trail. My wife usually wants me to for the sake of comfort. And it shouldn't bother me since I have two really fast inflation systems, my ARB Twin and an air tank.
Toyota cruise is just aggressive as hell. Never had a truck before the taco or the GX that would go 5-6mph over the desired cruise setting before it would upshift. Frustrating.
Yup. I’m so used to my Mercedes cruise control being so smooth and seamless. Granted they actually have power to move themselves
The problem is the algorithms on regular cruise are predictive and can't factor in hills and so forth properly. It basically sets a range that if you go under desired speed by X amount then you will add torque to achieve set speed, but on the other hand overspeed can't do anything on a downhill without active braking. Some other manufacturers allow a lot more underspeed which results in even more overspeed. The feedback loop isn't the best and it depends if they are looking at output shaft speed or wheel speed. Wheel speed is more accurate but older generations are not torque secure sensors meaning they can't use it per CARB regulations. And most newer vehicles with radar cruise or adaptive will brake for you if you do overspeed which results in changing the brakes more often. It's a complicated system lol. I drive a lot of various vehicles for my job and can attest that the Lexus is one of the better systems for a basic non-adaptive cruise control. It does what it is supposed to, but some people prefer more gradual control rather than reactive. My prior vehicle had a slow to react system and imo it was worse than a more reactive one. Both end up overspeed, just one doesn't downshift when you request it. Likely you could improve a lot of this with trans schedule changes since your cruise control is just a torque request PID and the reason it will or won't downshift is if you request enough torque. Just need to update the thresholds to get a smoother performance. They are set high for each gear for better fuel economy so you don't shift as frequently meaning you need to dig deeper into the pedal to get a downshift.
