Bigger tires and gear ratios

[norocksplease]

We're considering putting a lift and some bigger tires on our 06 LBZ 4x4. I'm somewhat worried about the larger tires may change the gear ratio to a point that would greatly affect fuel economy, and more importantly, reliability. When I suggested 4.56 gears the local shop, Off Road Unlimited, they suggested 4.10's to keep the motor more lugged out to help with passing ability. At the moment the trans runs almost oddly cold, I've heard some say that they are reaching nearly 200 degrees when towing and this thing hangs in the 160 range. I suppose it's nothing to complain about though. We plan to put a 4 inch catback exhaust on the truck and nothing more mechanically speaking seeing as it works just fine. Maybe an intake.

Is the dealer right?

Will putting 35 inch tires do any bad wear on the drivetrain?

We are currently towing 10,000lbs, but may get a bigger trailer which equates to a 14,000lb 5th wheel.

Thanks

[DmaxMaverick]

Curious.....
How do you plan on getting a truck with 35" tires, and a lift to accommodate the tires, under a fifth wheel? I have a tall, heavy fifth wheel (2005 32' Mountaineer) I tow with my truck, and it has 33" tires with no lift. The height is marginally near the limit, and can exceed 13'6" with the airbags full up. With a lift, and taller tires, a full height 5'er would be taller than legal, not to mention very unsafe. If you had a 5'er, uncommonly short, you'd have to raise it at least the height difference of the truck lift, plus the tire size increase. A 14K trailer would be a hazard to tow at that height. If you want a trailer that large, better to stay with pullers, or find a 5th wheel designed to be towed by a truck that tall.

The drivetrain won't be too much of an issue. You could change the gear ratio to 4.10 to get the ratio closer to design, but 4.56 would be too much, IMO. I tow 14K easily with OEM gears and 33" tires. 6th gear would be out of the question for towing that much, except maybe on the flattest of roads. I tow OD (5th) most of the time. At first, I had considered changing mine to 4.10, but after I towed a while, I discovered it towed better at a lower RPM. I had the option at the time to trade my brother's 8.1L gasser 4.10 gears for my 3.73 (he could pass anything but a gas station).

[norocksplease]

weekend warrior will flip the axles and that accomodates most lifted trucks. They are at a legal height, level, and tow great with trucks with up to 8 inch lifts.

[Riverholic]

I have an 8" lift with 37" tires. I am wondering if changing to the 4.10's would be good for me. My local diff shop said that it would be a waste cause diesels love lower rpm's cause their torque. I have the hot juice and am getting the tranny rebuilt with the suncoast kit now but should i change the gears also? It only pulls my boat which is about 6k and is mostly a daily driver. Any opinions?? Thanks!

[DmaxMaverick]

I have an 8" lift with 37" tires. I am wondering if changing to the 4.10's would be good for me. My local diff shop said that it would be a waste cause diesels love lower rpm's cause their torque. I have the hot juice and am getting the tranny rebuilt with the suncoast kit now but should i change the gears also? It only pulls my boat which is about 6k and is mostly a daily driver. Any opinions?? Thanks!

Even with the upgraded tranny and juice, I'd suggest 4.10 gears with 37" tires. Towing and hot rodding will take it's toll on other drivetrain components, and make grade braking just about useless.

Rather than rebuilding your diff's, find someone with a gasser and 4.10's that's whining about his economy. The swap would be a piece of cake, and involve only labor. I was considering just that until my brother sold his '02 8.1L/4.10.

[norocksplease]

Even with the upgraded tranny and juice, I'd suggest 4.10 gears with 37" tires. Towing and hot rodding will take it's toll on other drivetrain components, and make grade braking just about useless.

Rather than rebuilding your diff's, find someone with a gasser and 4.10's that's whining about his economy. The swap would be a piece of cake, and involve only labor. I was considering just that until my brother sold his '02 8.1L/4.10.
Anyone wanna swap? Can you only swap with a big block owner? Or do the 6.0L's have the same setup?

Any other opinions that maverick's? Just want to be sure I hear plenty of opinions. If you agree please say so! :)

[DmaxMaverick]

Gotta be a BB. The 6.0L's came with the 10.5 diff.

[IUPAC]

If the 6.0L has the 10.5, what size diff does the BB or Dmax have.

[WhiteTruck]

11.5" big dog