Aaah, now I get it. The math all makes sense. But I’m unclear what problem you’re trying to solve? You’ve got more info than I have here.
It sounds like there’s a max trailer weight limit that depends on whether you have the tow package or not, and you want to exceed the limit for your current truck by modifying it to be closer to the tow-package equipped variant of that same truck which has a higher limit that’ll support your hoped-for new heavier trailer.
If that’s so, then I’ll suggest that without a detailed list of all the things they change for the tow package you may well be fixing something that ain’t broke. You may been bigger brakes or a bigger tranny cooler more than you need a different differential ratio.
As to trying to lock out certain gears, the tranny computer ought to be smart enough to not shift into a gear so high it detects engine lugging. So you the driver ought not need to worry about that.
On a related note, if you do install a different diff ratio, various points in the vehicle software need to be reconfigured to match. Could be in the tranny computer, the engine computer, the instrument cluster computer, or all three. If that’s a factory-approved mod with a factory-approved install procedure, that’ll all be addressed. If not, and this is more shade-tree engineering even if installed at the dealership, you may find the tranny shifting at the wrong RPMs, the speedo way off, the engine lugging, etc.
Not necessarily a show-stopper, but a question to know the answer to before laying out the bucks.
if their problem is a FIXED cost problem, producing more will REDUCE losses.
if their problem is a VAR. cost problem, producing more will INCREASE losses.
So, If I were a stakeholder, you can guess what my Q. would be …
.
I’d assume companies of that size have ABC-Costing (Activity Based Costing) - where every department (semi)anually evaluates their activity and for whome they are working (ICE vs. EV) … and asign their cost structure in base of that …
That was pretty much standard 30 years ago when I was more involved in that kind of work
bear in mind that your drive wheels (the one with the dunlup rubber ) are also part of your drive train.
So, using 10% “smaller” tires has the same effect on your vehicle than increasing the rear-diff ratio by 10% … (say from 4:1 to 4.4:1)
Might be the cheapest workaround if you find your current config. “lacking” … just get a pair of smaller tires and swap over for a given trip - problem solved for less than $100.00
(if your truck is 4x4, you need to change of course all 4 tires )
.
2nd cheapest solution:
get aftermarket ring/pinions … poke around 4x4 forums for names/models … those can normally be had for not too much money and you will find lots of people use those (and hence have some sort of reassurance from those not falling apart.
Have it installed by a good 4x4 place in your area, as setting (marry-ing) up a ring-pinion is best left to the experts (you need to get the backlash right) … but for any decent 4x4 shop that should be a pretty standard job.
Having this done at Ford, is somewhat akin to buying a cabin air filter there … chances are those are OEM parts (e.g. Bosch) where they charge you 3-10 times the market price … so of course their quote was one of “prepare to be an@lly raped” by our service dept.
ooops … LSL has some rather good points here … (I was going a bit of my “beater-truck” 4x4 experience) …
of course, if you have a new-all-electronic-everything truck, a different set of rear-tires vs. front will mess up a whole lot of things … you’d def. will throw an ABS-error code (as the “system” will have trouble explaining why the rear tires run at 60mph while the front tires run consistently at 55mph (or vice versa - i’m too lazy to think it through now ) …
also, of course smaller tires will not help you if your problem is “undersized braking system” for those kinds of loads …
again, I am coming mostly from basic-as-dirt, 4x4, manual shift stick shift trucks that couldn’t care less about that kind of things
… so, in short going back to the dealer might be your best bet, if “reprogramming” your truck is needed (and I think it is) … lube up!!!
I watch a lot of car repair videos on You Tube, especially Eric O at South Main Auto Repair. He rarely replaces the calipers and when he does, there is an obvious defect. The last video I saw him change a caliper was on a 1990’s model Camry and he only changed the one bad caliper. That was because the piston was frozen into the caliper. The other 3 calipers were fully operational. The past year I have done brakes on 4 vehicles, all I changed were the pads and rotors. Everyone has been happy with the job I did.
I’m only considering differential changes done by the dealer/mechanic network. Including the requisite software/firmware upgrades as well, to ensure odometer, shift points, and the like are kept to factory specs. No shade-tree stuff (although I’m not above that at all).
Sorry, I need to add more detail. Our former truck (that died in the accident) was a diesel. We replaced it with a gas version which, surprisingly, allows more tow capacity because the diesel ecosystem isn’t gobbling up my GVWR any more. In pilot speak: I have a larger useful load*. Surprisingly, we are now within range of some of the 5th wheels we’ve been coveting, and the only remaining limitation (at the high end) is this truck’s rear axle ratio. My curiosity stems from my reluctance to skate along at the very top of a tow-vehicle’s capability, but in this case I’d only be pushing the limits of the 3.73 ratio. The 4.10 would give more breathing room for mountainous travel. So I was curious if we could achieve the same effect by lowering the transmission gear by one (with the shift limiter in the cab).
*In most recreational trailering setups, the limiting number is the truck’s GVWR. As heavier trailers are considered, it hits the max before any of the other towing limits. This is because the truck must bear ~20% of the trailer’s weight on its rear axle. Every additional 100 lbs. of truck payload allows 500 more lbs. of trailer. My useful load increase in this new truck is an astonishing 1500 lbs. I can “legally” tow a fifth-wheel up to 13,500 lbs. now.
probably yes, as that is the equivalent of running in a lower gear on a stick shift … supposing the overall weight is within the tranny’s spec’s …
this is of course not a out-of-jail card that comes for free, as you somewhat convert your nice truck into a semi (high-revs in a low gear going up an incline)
but if it is just for short uphill climbs, I dont see why not … m
With the impending demise of the gas-powered muscle cars, demand is high for all the last, juiced versions of the big names (Mustang, Camaro, Challenger, Charger).
There are about 13,000 U.S. orders for the 2024 Mustangs, Ford says, which also can be equipped with a four-cylinder turbocharged engine. Of those orders, 67% have the V-8, and more than a quarter of the people seeking that Mustang want the six-speed manual transmission
That’s for the 2032 model year. The current requirement is new vehicles sold in the U.S. will have to average at least 40 miles per gallon of gasoline in 2026, so a pretty big increase.
Seems extremely weak to me. I will be very disappointed if that number isn’t reached just from EV adoption alone. Reading between the lines a bit, it seems like CAFE may be intentionally setting an unaggressive target so that they don’t conflict with EPA rules.
Completely unrelated to the Rivian, but since this thread is for general car talk, that reminded me of a story I saw on 60 Minutes or a similar show back in the 1990s, about how the stock tires on the Acura NSX didn’t last very long. As I recall Honda’s response was that they were special high performance tires made of softer rubber, and they weren’t supposed to last as long as normal tires.
And I’m sure Honda was 100% technically correct, performance tires aren’t expected to last as long as the tires on a family sedan. But to all the non-car people who watched that story, it probably came across as “OMG, Honda is putting crappy tires on their expensive sports car!”, which seemed to be the narrative the reporter was going for.
Former NSX owner here.
The OE tires on the NSX were soft, but Honda wanted that car to be the best-handling car on the market, so they specified a lot of camber. The cars handled well and tire wear was acceptable—as long as it was driven aggressively the tires would wear evenly. But if the owner drove the car mildly, the camber caused excessive wear to the outside edges of the tires. IIRC, Honda later specified less camber due to complaints about tire wear.
Having ridden in a Rivian, you could easily make the tires last six miles. That is a seriously fast truck that weighs 7000# and corners like a sports car (well, flat anyway, due to the air suspension). That being said, my buddy cracked both the windshield and the rear windscreen and hit a deer, and it’s been a bit of a nightmare since the nearest service center is 6 hours away. Really cool vehicle, though.
All EVs require special tires due to being heavier due to the batteries than conventional internal combustion cars, and the additional torque that electric motors can provide.
As it turns out, this excessive front tire wear can likely be tied back to Rivian’s “Conserve” drive mode. In order to maximize range, when you switch to Conserve, your Rivian switches from four-wheel drive to front-wheel drive and lowers the ride height. Sending more than 400 hp to the front wheels in a truck that weighs more than 7,000 lbs is bound to increase tire wear, but it appears that lowering the suspension also causes problems.
Apparently, the lowest ride height causes toe-in and more negative camber, which can accelerate and also cause uneven tire wear. According to one owner who drove in Conserve mode for 6,000 miles, the front tires lost an entire millimeter more than the rears. Which seems bad but also explains why Rivian has reportedly told owners not to use Conserve mode over long distances. Owners have also reported issues with the stock alignment.
) are also part of your drive train.