what are your plans with the truck? Lift …bigger tires? Leave it stock? Your big issue will be when you’re running unloaded those 4:56s on stock 32 inch tall tires will bring your RPMs up when you’re running on the highway. You might wanna go to 4:30s. If you’re lifted the 4:56s will actually bring bayou back in yiur engines power range
completely different vehicle but I was running 3:73s on a Chevy truck with a 454 and went to 4:56 with stock 265/75/16 had to run a 35 inch tire to get my RPMs in a useable range. It was revving way too high in the freeway. Towed like a freight train.but wasn’t user friendly when tooling around.

 

Not lifting and no plans for bugger tires. Currently have 285, which I like and equal approx. 33 inch tires. The truck sees some around town use, but not much.

 

ok I figured you would be somewhere near a stock tire size. Personally I think you’ll be happier with 4:30s or even 4:10s if you’re not planning on going bigger or lifted. . On my 7.3 F250 I once had these mud terrain 305/75/16 and with 3:55 gears I could definitely feel the tire size a little bit since it was a auto. Nothing major….. It was just like everything was off a tad. I eventually went back to the stock 265/75/16 and I was much happier. I didn’t have a tuner back then. I have one now but haven’t tried it yet.. . That’s something else you may wanna look in trying. You could be feeling the same “off” sensation from the tire height difference and a tuner may adjust for the tire size and add a bit of hp also before you go into a expensive gear swap. Or if you have a tuner see if there is a option for adjusting tire size. I used to do gear swaps for myself or friends and the shops around here charge about $5/600 plus for labor. A full swap will run $1000/$1200 these days per axle. That’s a big chunk of change if you got a 4x

 

If your yearly mileage is primarily towing and just a few thousand miles and that will be the case for the rest of the time you own your truck go with 4.88's. Definitely no higher than 4.56 (lower numerical-higher ratio).

I regeared our truck when we first purchased it and I went with 4.30's replacing the factory 3.73 limited slip. No particular regrets but our yearly usage patterns changed in the mean time with towing being 95% of our yearly mileage. What a pleasant difference the 4.30's made in our towing experience!! Had I known that our primary usage would be towing we would have gone with a 4.88, or at the very least the 4.56. The lower gearing keeps the RPM's in the sweet spot at highway speeds and downshifting is kept at a much lower frequency.

Good luck. You're going to LOVE those lower gears for your towing needs!

 

4:88s on a stock truck with stock or close to stock tire size is too much gearing for all around use even if it’s a dedicated tow vehicke.. . He’s only running a 29.75 inch tire. Every gear ratio you go up you’re adding about 140 RPMs (give or take 15/20 rpm) . 4:88s will give him a lot of power but his engine will be in the higher rpm range. And fuel economy will probably be in the mid single digits. He needs to adjust for the larger tire size and maybe a bit more. 4:56 would be the highest I would go on the very upper limit. No way I would run 4:88s in this situation.

 

dualwheel, have you ever run a 6.8 with 4.30/4.56/4.88 gears? It doesn't sound like it, if you read my post quoted above you will see that I ran my 4.88s for 2 years with 32" rubber, the OP is rolling on 33"s, I don't know how you figured 29.75" for his 285s. And cruising a 6.8 at 2400 RPMs puts it right in the sweet spot for great towing torque. That combo coupled with a good tune to improve the shift strategy really makes towing nice.
My 8,000lb EX described above gets 14.5 MPG at 65 MPH on the highway, with the AC on running unloaded and has logged multiple trips over 400 miles towing the 12K TT at 9.5 MPG.

 

That was supposed to be 32.9. Not 29.75. Not sure how I wrote that. . Either way stock 3:55 or 3:73s should have his v10 in the 2000-2200 rpm range at 65. With 4:88s that will put him in the 2500 rpm range. Give or take a few RPMs . . I’m not saying he can’t run 4:88s…I’m saying it’s too low a gear for his intended use.. You simply don’t need to go that low. I just never felt that’s a good idea on a tow vehicle/street truck.. the whole idea of regearing is to keep it in a range close to factory parameters. Yes you can fudge a bit run one ratio lower for a bit more oomph or like you “I’m gonna lift it later so I’ll run this gear fir now” situation. Anyway….If he doesn’t mind running 2500 RPMs at 65 go for it. If he needs to run at 70/75 he’ll be running that much higher RPMs.. If he was lifted running 35/37s…yes 4:88s would be a good choice. And yes I have friends with V10s and I’ve never put a 4:88 gears on any of their trucks. The most I did was 4:30s on a buddys F350 who I put a 6 inch lift and he wanted to run 37s. The 4:30s were plenty for that truck. The lift is now in my shed. I bought the truck from him after he blew it up cause I was gonna rebuild it but he just hammered it and it would cost more than buying a nice clean crew cab. I’m not saying you’re wrong.I’m saying you’re offering a very tight parameter for a gear swap. . I’ve been doing gear swaps for 25 some years on trucks for friends and it’s just my personal opinion.

 

These trucks were available stock with 4.30s. Right off the floor, with factory tires. There's no way I'd drop a couple of grand to go with 4.10 or 4.30 and (with his 33s) be higher geared than what was available from the factory. What may be a perfectly adequate ratio on a 454 or even work alright on a V10 that's lifted, but not towing is entirely different than what the OP is asking. I think for his needs 4.56 is ideal

 

01v10... local reputable shop wants 2400... (4x4)... worth it?

 

I priced 4.56s and a detroit for mine a while back and the local 4x4 shop said they were having a sale and the reduced total would be $3K. I still haven't done it, but I intend to. I think it's worth a couple of grand to have your truck function properly for your intended use. It's a once and done thing. It's not cheap, but if you're planning on keeping the truck for the long haul, I'd say it's the right move.

 

I didn’t say my buddy doesn’t tow. He just doesn’t tow a lot. He probably tows 5/6 times a year. Which is what a lot of people tow.. And nobody is arguing that he doesn’t need some gear upgrade to help towing.. It’s a matter of how much gearing he needs. Just because 4:30s are stock gears doesn’t mean they aren’t the right gears for the application.. It doesn’t matter if they come from the factory with such gearing…his truck didn’t come with such option. If it did he may not want to change anything If he’s not lifting the truck you can do such thing as overgear a truck.normally regearing is done to accommodate a larger tire or add a bit of extra down low. I already said I wouldn’t go more than a 4:56 ratio especially since there are no plans to lift it and add larger wheels and tires.


I have two trucks. Identical in most ways as far as engines, cab options and chassi/bed. Both 4x4. The only two differences are one is a Dually the other is a single wheel and one is a auto the other is a standard. Which is no big deal
one has 3:55s the other has 4:10. There is a HIGE difference between the two in towing. Both trucks run almost identical height tires 265/75/26 and 235/85/16 About 32 inch tall. At highway cruising the RPMs are about 150 revs difference. If I geared either to 4:88 I don’t think they will be as drivable as they are now. The 3:55 equipped truck would get a major upgrade in tow and overall drivability at the expense of fuel mileage. I don’t use it for towing so I’m fine with it as is. I may regear it someday but I doubt I’ll go through the expense. If I sell it the next owner can do what they want with it.

when I was running 305/75/16 on my single wheel I could feel the difference. Everything was a bit off. I could of regeared but I knew I wasn’t gonna keep that size tire on there. In fact I took the tires off within 6 months. They were noisy, hunted around, horrible in wet or dry handling. That’s why I dint run mud tires anymore. But in that instance 4:10s would of been a great choice. Either way OP can run whatever gear he feels is best fir his application. I’m simply giving him my observations. Unless he dies the work himself getting the wrong gears will make him unhappy with the way the truck performs, but his wallet will feel it at the gas pump and at the possible paying twice to get it right.

 

(According to online calculators) The difference between 32s with 4.30 and 33s with 4.56 is about 60rpm at 65mph. It's essentially going to run like a factory truck with 4.30s. My last V10 had 4.30s and 33s. It was a big improvement over my current one with 3.73s and 33s. I agree that if he had 4.30s he probably wouldn't be considering changing them, but since he's thinking it he might as well skip the 4.30 and go 4.56.

 

Yes the difference isn’t much at that spread between 4:30 and 4:56. Especially if you’re playing with tire sizes also. The only time it may make a difference if he ever wants to go to the 265 stock tire size. That will bump up the RPMs.

 

I read the OP's post as a desire to regear a limited use truck that would be pretty much a dedicated tow rig with very little unloaded miles, very similar to my V-10's usage. I think your numbers are little off too, on my EX with the 4.88s and 32" tires I verified the speed with a GPS and recorded the RPMs via my Ultra-Gauge and at 65 MPH it was turning 2430 RPMS, thats not too high for these rev happy modular tens and he will be a bit lower on the revs due to his 33" rubber vs my 32". With my true 35"s and the 4.88s I'm at an effective 4.39 ratio and spinning 2230 RPMS at 65 MPH, makes for a solid tow rig for our very heavy (12K lbs) TT, sometimes on longer steeper grades I almost wish I had gone with 5.13s, which would be more like it was with the 32"/4.88 combo, it towed like a locomotive back then. Regearing isn't only about getting back to a factory ratio thrown off by taller tires, it's also a good choice for improving on those factory option ratios for rigs that aren't going to be used like a typical daily driver truck and are seeing the bulk of their miles with some high profile heavy TT on the hitch. There are better ratio options for those trucks than what the factory offered in my opinion. Don't fear the gear (on a dedicated tow rig!).

 

well my numbers aren’t going to be exact to the tee. So yes I’ll be off slightly. It’s a approximate estimation of RPM, tire size, as to where he is and where he ends up. There will always be slight differences. There is no exact best gear…it’s all a can you live with this or that, this is a advantage, this is a disadvantage if you run x gear ratio vs y gear ratio.
yes with 4::88s it will pull like a locomotive….i mean….it better. I have a play yoy 89 GMC with 4:56 and 275/60/15 and I barely touch the gas and the tires spin. And this is a stock TBI 350. When it had stock 3:08 it was a dog when I was running 35s. I regeared it and threw a shift kit and a servo and it would bark the 35s hard. I have to regear it now because the tires are too small now and it revs too high for cruising.

I don’t think anyone here is wrong with their suggestions. I don’t mean to come off like my opinion is the only one that matters. I hope you guys dudnt take it that way. It’s just a opinion of 30 years of working on vehicles as a hobby. I think OP is going to have to decide what he wants more. There are pluses and minuses to any of the ratios he chooses to use be it 4:40, 4:56 or 4:88. That will 8mpsct the drivability, fuel mileage etc. . While they are close on ratio to one another any of them will make a difference from his current set up. Some more drastic than others.