gears/tire size for towing. planning full on gear swap, maybe more....

[oldschool17]

ok, i posted here before and got some great info, and since then have done my homework. i have an 06 ext cab 4x4 with the 5.3 in it, auto tranny with tow package. i tow a pontoon boat (not very aerodynamic lol). my problem is my gear ratio.
3.42 uuggghh.
i am doing a gear swap before next summer. this is where i need some advice.
i am running a 31" tire.
i was debating on keeping the stock size tire and going to 3.73, or putting in a lift and running 4.10 with 35" tires.
with the 4.10 and 35's, my theoretical final drive should be about the equivalent of a 3.80 ratio. this is figuring rpm at 60 mph versus the 3.73.
basically will the 4.10 with larger tires perform better than stock size tires with 3.73? or is it a wash?
now my debating point is this. will 4.10's even with the bigget tires be better for towing (low end torque) than the stock tire size with 3.73?
i was thinkin on the lift to raise the trucks height to maybe cut the air better than it does now. when my boat is on the trailer, the floor of the boat is level with the top of the bed. basically acting as a large sail.
i welcome all comments, except sale the boat. lol. i have saved for 11 years to buy the boat, it aint going nowhere. lol.
thanks in advance.

[grayblazer]

I think that going from 3.42 to 3.73 is a waste of time and money as you probably won't be able to notice the difference. Years ago I went from 3.73 to 4.10 and was really disappointed when I went for the first ride and didn't notice anything. I do automotive testing for a living now and this has allowed me to drive identical new trucks with varying gear ratios and it's really hard to tell the difference between "one step" ratios (i.e. difference between 3.42 and 3.73, 3.73 and 4.10, etc...). Also keep in mind the GM offered 4.10's as a factory option in the 5.3 trucks. My dad had about a '00 and my brother-in-law had maybe an '06 that were 1500's with 4.10 gears.

Going to 35's and 4.10's would likely be worse. The rpm at cruising speed is almost identical to what you have now, but you now have quite a bit more aerodynamic resistance from the lift, and the larger tires and heavier causing more rotational mass (adding 50 lbs. in tires and wheels is about the same as adding 500 lbs. to the truck) and they will have more rolling resistance (assuming you are comparing similar styles of tires with the difference in size).

With stock tires I would go 4.10, with 35's I would go at least 4.56 if not 4.88.

[ToyHauler]

i agree stock tires and 4.10's. big tires are the opposite of what you want to do for towing and braking, and the lift usually decreases stability and ability to control the load. off road tires are also more squishy further decreasing control. the only thing with 4.10's is if you do more highway than hilly or stop and go your mileage will decrease, but your towing mileage will get better.

[oldschool17]

Thanks. i know right now with the 3.42 gears its dead. 60 mph is about 1500 rpm. in your opinion would staying with 31" tire and going to 4.10 make a noticeable difference? i figured out the rpm for 4.10 and 31" tire to be about 1750 at 60 mph.

[Jon4x4]

35s and 4.88s

[ToyHauler]

how much difference is hard to quantify. i have 3.42's in my yukon and im hauling my camper and other lighter things, but the camper is 6k and square. the 3.42's arent that bad in 3rd because the engine comes down to a tolerable level when going 55-60. but ive had a couple 2500's with 4.10's for work trucks and it increases the amount you can tow in od but with my camper you would still be in 3rd and now the engine is buzzing. then you have the cost of buying two sets of gears, having them installed and you have to correct the computer for the gear change. not worth it in my opinion but then again im not the type who has to be in the left lane keeping up with the cars going ten over with a big camper behind me either.

[jacob.mellberg]

just some more food for thought...

i have an 01 sierra 1500hd with the 6.0L Vortec and 4L80e tranny, its lifted 4 inches on 35 inch tires. I had the stock 4.10 gears and was getting about 1700-1900 rpms at 60mph, with no towing power for heavier loads.

i upgraded the gears to 4.88 because i wanted to keep the 35 inch tire but wanted more low end power. now i'm at about 2100-2400 rpm at 60mph, eats more fuel but can pretty much tow anything. competes very well with a 2500 truck with either the 6L80e or allison 6 speed trannys with same motor.

now put my truck up with a 2500hd with a duramax or any diesel for that matter and i'm dead in the water but for what i use the truck for its perfect.

hope this helps, good luck!

[mpope2]

ok, i posted here before and got some great info, and since then have done my homework. i have an 06 ext cab 4x4 with the 5.3 in it, auto tranny with tow package. i tow a pontoon boat (not very aerodynamic lol). my problem is my gear ratio.
3.42 uuggghh.
i am doing a gear swap before next summer. this is where i need some advice.
i am running a 31" tire.
i was debating on keeping the stock size tire and going to 3.73, or putting in a lift and running 4.10 with 35" tires.
with the 4.10 and 35's, my theoretical final drive should be about the equivalent of a 3.80 ratio. this is figuring rpm at 60 mph versus the 3.73.
basically will the 4.10 with larger tires perform better than stock size tires with 3.73? or is it a wash?
now my debating point is this. will 4.10's even with the bigget tires be better for towing (low end torque) than the stock tire size with 3.73?
i was thinkin on the lift to raise the trucks height to maybe cut the air better than it does now. when my boat is on the trailer, the floor of the boat is level with the top of the bed. basically acting as a large sail.
i welcome all comments, except sale the boat. lol. i have saved for 11 years to buy the boat, it aint going nowhere. lol.
thanks in advance.
If you step up to 35s, go at least to a 4.56. If you stay between 31-33s consider motive 4.30s

[jacob.mellberg]

i'd say yes AT LEAST 4.56 with 35s but it depends on what the curb weight of the boat is after you've pulled it out of the water and there's water on it and your gear in it still. basically i'd say with a 35" tire and 4.56s you'd be good for a 4K-7K pound haul no problem but if you venture up in the 7K-10k pound range i'd look at getting 4.88s with a 35" tire. you definitely want to consider how often you are going to tow and if you are using the truck daily without hauling/towing anything because (just like my truck) 4.88s and 35s are going to cost you more fuel. but on the other hand you don't want to have some gear work done and then not get the performance increase you're looking for.

if you upgrade to a 33" tire then i would say don't get anything bigger than a 4.56, 4.88s are pretty beastly!

hope this helps!

[scarybowtie]

31" + 4.10s or 35" and 4.56 minimum. I have 33s and 4.56s and its perfect imo. At 70mph its at around 2300rpm and will tow a decent load in o/d

[TEXAS CHARLIE]

Do not tow in overdrive

[scarybowtie]

Do not tow in overdrive

I may be wrong but would he's not be the only reason to not tow in o/d? My tranny has never gotten over 200* with a load in o/d.

[93ChevyTBI]

31" + 4.10s or 35" and 4.56 minimum. I have 33s and 4.56s and its perfect imo. At 70mph its at around 2300rpm and will tow a decent load in o/d

I'm running 33's and 4.10's and for some reason turning the same rpm.....2300 at 70 mph. It tows any weight pretty good at 70 but tows better at 75 mph when the rpm's go up to 2500. I noticed this towing my boat to the lake this summer. Lock in cruise in O/D at 75 mph and it does great......tc doesn't even unlock. At 70 mph, it has to kick down on hills.

[scarybowtie]

That's odd, you have a 4l60 also right? Maybe the tires are just a little different height. Mine is actually at 2350 rpm at 700 but I figured there would be a lil more difference

[93ChevyTBI]

That's odd, you have a 4l60 also right? Maybe the tires are just a little different height. Mine is actually at 2350 rpm at 700 but I figured there would be a lil more difference

yes the 4l60e. Tires are BFG 33x10.50x15 and speedo has been calibrated to 100% perfect with a GPS. I mentioned it on here before but no one had any answers for it. I tell you what though, I was surprised as hell that it would tow a 20 ft Bass Tracker Grizzly up the Smokey Mountains of Tennessee in O/D.....surprised the hell out of me really. Then I was confused as to why it had trouble pulling my 18 ft Grizzly. It took me a few minutes to realize the speed and rpm difference. Sped up to 75 and hit cruise and all was good again. I pulled a heavy duty trailer and Bobcat a few weeks ago in O/D and it did fine too, although there were no hills. I need to get a temp gauge on the tranny in all honesty.

If anything goes wrong, I'm putting a 383 in it but it's doing great and only has like 30k on the rebuild. At the current rate of driving, it'll last another 8 years on the rebuild unless the towing shortens its life.

[jacob.mellberg]

Over drive towing is fine, thats what its for...hence some called tow/haul...same function. but i would avoid using cruise control when towing or using o/d

[scarybowtie]

yes the 4l60e. Tires are BFG 33x10.50x15 and speedo has been calibrated to 100% perfect with a GPS. I mentioned it on here before but no one had any answers for it. I tell you what though, I was surprised as hell that it would tow a 20 ft Bass Tracker Grizzly up the Smokey Mountains of Tennessee in O/D.....surprised the hell out of me really. Then I was confused as to why it had trouble pulling my 18 ft Grizzly. It took me a few minutes to realize the speed and rpm difference. Sped up to 75 and hit cruise and all was good again. I pulled a heavy duty trailer and Bobcat a few weeks ago in O/D and it did fine too, although there were no hills. I need to get a temp gauge on the tranny in all honesty.

If anything goes wrong, I'm putting a 383 in it but it's doing great and only has like 30k on the rebuild. At the current rate of driving, it'll last another 8 years on the rebuild unless the towing shortens its life.

I run 33 x 12.5 x 15, speedo is dead on as well. I finished a 6.0 swap in mine a while back and towing improved drastically. Sounds like you have a stout 350

[joelvv]

The very simple way of doing this is to just tow in D and forget about the rest of it. I have towed up to 10000 lb with a 305, and it amazes me how well I can pull the load. I can maintain 55-60 mph up most hills without coming out of lock up. It's better for the tranmsission to be in D when towing anyways. I've also done mileage checks and pulling 4000lb going between 4th and 3rd to keep it locked up, I got 10mpg. Towing 9500 lb I got 11mpg staying locked up in 3rd. Both 55mph. It doesn't necessarily matter if you keep the heat down, it does make a huge difference, but from what I understand, 3rd gear is simply stronger. The clutches will hold tighter than 4th gear.

[93ChevyTBI]

I'm not doing 55 mph 100 miles one way down the interstate though. Likewise I'm not gonna run 4000 rpm's in 3rd trying to do 70-75 mph.

[joelvv]

I'm not doing 55 mph 100 miles one way down the interstate though. Likewise I'm not gonna run 4000 rpm's in 3rd trying to do 70-75 mph.

I was replying to the original posters question. You already have 4.10 and 33" tires, not 35". You'd be running under 3400 rpm not 4k

[scarybowtie]

I'm not doing 55 mph 100 miles one way down the interstate though. Likewise I'm not gonna run 4000 rpm's in 3rd trying to do 70-75 mph.

I agree completely. I know 3rd has more pressure applied to the clutches than o/d (or so I've heard). But I'm not gonna turn 3500-3600 rpm down the highway to pull in 3rd. O/d towing has worked fine for me for years. Now of course there are exceptions, I'm not gonna leave the truck in o/d while towing the 26' toy hauler. But for anything up to a full sized vehicle on my 20' trailer, o/d will be fine. It's not good to constantly lock/unlock the converter or downshift all the time. But mine doesn't at 70- 75 hardly ever. 3rd is easier on the tranny, but at those speeds its harder on the motor and fuel milage

[joelvv]

I was never implying you should run in 3rd at 75mph. The OP mentioned 60 mph. The engine is in a completely different place at 75 mph. A 5.3 peaks on torque at 4000 rpm and hp way higher yet. Rpm at 60 mph and 3.42, in OD is 1566rpm, D is 2250 . At 75mph OD is 1957rpm, D is 2812rpm. If he wants more power he wants rpm, closer to 4000 is better, but there has to be a balance between power and mileage. At 60 mph, you're better off in 3rd for the extra power, at 75 mph the rpm's are up some, meaning you may be able pull it in OD without unlocking. To the OP. In my opinion, if you're towing 55-60 mph, drive in 3rd and save the money of the extra parts. If you're driving 70-75 get 4.10 gears and tow in OD. 4.10 would get you better acceleration so if acceleration is lacking, that would help as well. If you're towing you'd be better off leaving tires as they are, unless you're going to be changing the brakes to something better.

[93ChevyTBI]

Mine has peak torque of 440 ft/lbs between 2000-2500 rpm. And that thankfully is my perfect interstate cruising rpm at 75 mph. It may have taken me 2 stabs to get the right cam but my 2nd choice could not have been better. I'm very happy with it.

[joelvv]

A 350 is a different animal than the 5.3. Torque between 2000-2500 would be doable(and obviously is) but would take a bit of work(if it's even possible) on a 5.3 to pull peak torque down from 4000 rpm. Sounds like I need to get rid of my 305. 440 ft lb torque sounds pretty attractive.