Hark! Do I hear a 4x4 conversion in the making?

 

Some day perhaps, but not right now, just want to regear the rear, to get back into the same power band as i used to be in before the wheels and tires.

With the new larger wheels and tires it drives fine without the trailer, but with my 30 ft trailer hitched up it is just not a good enough gear ratio for hills.

 

TrueTrac and G2 4:56. I use Redline gear oil. Running OEM size Michelin E rated tires. Very happy, so far. Next month we take delivery of a 28’ TT. We’ll see how it does in the North GA mountains.

 

4:56 is overkill for my purposes, i just want to get back to the same effective ratio, or close to, as I was before the new wheels and tires, it had great power, takeoff, and plenty of go go go.

 

If you thought the 3.73 felt good, you're going just love the 4.30. An Ex with 4.30 gears is like a jack rabbit compared to 3.73. You will "go Faster". I lost a few mph on the top with the 4.56 gears. With the 4.30 and 35s 2500 RPM was 80mph. With 4.56 2500 rpm is about 76 Mph. But the engine is in a sweet spot. Effortless 75 to 80.

 

Now I haven't tried my lockers in the ruff yet, but I vote for a selectable locker. You know when it's on or off. My Ox lockers are electro-mechanical cable driven. Of course, the True Trac cost about half the price.

 

So, I had 245/75/16 tires on it up until the new wheels and tires, so the effective ratio was 3.87, lets call it 3.90 for simplicity. Well, now it has 305/70/16 which changes the effective ratio to 3.6, which works fine with just the truck, but with my 30 ft trailer on, its not a good ratio and its like i am towing an excavator.

I thought about 4.10s, which would get me to effective 3.95, which i was going to do at first, but then thinking about it a little, and looking at the RPMs, im thinking 4.30s would get me even more pulling power, without sacrificing my ability to cruise at 80, and if i am in the middle of the desert hundreds of miles from nowhere on one of our long trips, more.

I was also thinking with the added weight of these wheels and tires, it might help justify the 4.30s as well.

My tire size is 32.8 per the calculator, i guess call it a 33.

I am still iffy, and thinking 4.30 might be too much.... and that i really need 4.10s....

 

I had 4.30 gears with BFG 33s, and my truck would roll at 80 with no problem. I understand you don't want to buzz the engine, but the 6.8 was built to rev. You stress the engine more with tall gears. I think your engine would be happy towing that trailer with 4.56 gears. Remember the 6.8 develops max torque at 3200 rpm. So, running along 2500 it's very happy. My wife and I have crossed that hump to Needles in the heat of day with no problems. Also, that stretch of road between Vegas and St. George no problem in 117 deg heat. Overhead cams and cross bolted mains get the job done. I pass lots of Escalades and Subs going up the Baker grade. I just set her on 75 up and down hills. The Caddys pass on the flat but fall back on the grades. I don't think 4.10 will be enough gear. If we were talking about a 460 maybe, but not the 6.8.

 

I have 4.30 with 34" tires which is an effective ratio of 3.90 if I remember right.. When towing anything more than a couple thousand lbs having something deeper would be nice.

 

I have 4.30 with 34" tires which is an effective ratio of 3.90 if I remember right.. When towing anything more than a couple thousand lbs having something deeper would be nice.

 

You need to get the 4.30's to get back to the performance with the 3.73's and your old 245/75R16 tires. I have stock 4.30's with 265/75R16's and I'm pleased with the performance with my 6.8L v10.

 

On 3.73s post all the motor work, i had no problem dragging the trailer around like a tinker toy, its the new wheels and tires that have complicated matters. Before those the difference between pulling our little tiny horse trailer, or the 30 footer was barely noticeable i could drag them both and still take off from a dig effortlessly.

Here are the trailers im speaking of for reference.

 

Given your propensity for maximum performance 4 30 will suit you well. Your 305's are approximately 32" tall. Before I stepped up to 315 70 17 and had 285 70 17, which were a hair over 32" , with 4.30 it was a night and day difference from the same 32 tire with 3.73. It was super quick and like driving a different truck.

 

Since everyone that has driven (and towed) with both 3.73s and 4.30s remarks how much better the 4.30s perform I can totally see why you only want to return the effective ratio back to 3.73-ish………..NOT!
In your situation, if I was planning to keep the the tires at 33” I’d go with 4.56s, if the tires are actually 32” then 4.30s. (The conversation seems to have given both measurements for your tire size and I’m too lazy to look them up myself) Gear swaps are expensive enough, to make it truly worth the expense go to a gear that improves the performance noticeably. I don’t know why you seem to think going to an effective 4.30 will kill your ability to cruise at 80 MPH, it won’t. I ran my 4.88s for two years with 32” tires, granted here in the Mid-Atlantic we can’t cruise at 80 unless we are looking for a meet and greet with the local law but it effortlessly cruised at 70 MPH at 2600 RPMs with the 4.88/32” combo. And of course it towed like a locomotive!

As a side note, for this discussion the trailer length isn’t really a factor, what do the trailers weigh? It the extra weight, not the length that has dropped your performance.

 

The Red one is all steel, but must not weigh much because i scarcely even feel it there power wise except for when im braking and the hitch shifts forward and then back again.

The 30 footer, on the factory sheet lists its weight as 4000 lbs empty, but i feel it back there more than the red one, but im also thinking there is a drag differential as well. While it is a V nose, the V is not as aggressive an angle as some others ive seen, and i avoided the flat nosed trailers for that reason, the Red one has a much more rounded and organic front to it.

I looked for a weight on the red trailer and it was not listed. We did about 15 trips with it of 50 miles, hauling our stuff when we moved 12 months ago, and i literally could not tell it was there even loaded to the max. Despite the counter statements of others, the truck already feels like a new truck with all the work i have done.

Using this calculator i factored that the old tires were 30.5, and the new ones are 32.8
https://tiresize.com/calculator/
using tire: 32.8, Trans ratio: 0.71 on this calc, and comparing speed and gear

Using this calculator i determined stock 265/75/16 with 3.73, and a new tire size of 305/70/16 yields a effective ratio of 3.6:1
and that stock 265/75/16 with 245/75/16 yields an effective ratio of 3.87 so right at 3.90 is where my prior and preferred effective ratio was.
https://tiresize.com/gear-ratio-calculator/

4.30 already steps me over the 3.90 preferred effective ratio and takes me all the way to 4.15, I'm not that guy who values launch power over top speed, i like a trade off of both, and I live in the middle of nowhere, so even going for groceries is a trip. (Just finally got Starlink approved, Should be here in about a week then i can kick this D-S-Smell.)

I think 4.15 effective is a good place to be, should net me a little extra power compared to what i was used to before, but keep the RPMs low enough i can still have a good cruising speed.

Based on the math, and my usual cruising RPM of 2400 right now on 3.73s, my new cruising RPM would be 2800, when im coming in or going out, to nowhere ville.
https://www.crawlpedia.com/rpm_gear_calculator.htm