Towing with 35's and 4.56's or 4.88's

[Vortec Lover]

sweet man- thanks! rep is in order

 

[RyanR]

Sorry guys our trannys aren't 1.1 ratio's!!! Ignore above... I calculated this at .74 final ratio. 4L80E's end at .75 and the NV4500's are .73.

3.73's w/ 35" Tires @ 70 MPH = 1800 RPM
4:10's w/ 35" Tires @ 70 MPH = 2000 RPM
4:56's w/ 35" Tires @ 70 MPH = 2200 RPM
4:88's w/ 35" Tires @ 70 MPH = 2400 RPM

that's the correct information given our transmissions final drive ratio's.. The .73 and .75 only make like 50 RPM difference at most so i didn't bother calculating the difference's between the two. Now realize if you put stock tires back on it'll be rapping out at like 3k so that would be bad..

Now that looks about right. I haven't even had mine up to 70 yet but with my 4.56s and 35s and at about 60 I'm taching around 1800-1900 and gas mileage has gone up tremendously vs the old 3.73s

 

[JScott23]

Yeah, the bigger tires need bigger gears or your gonna get terrible mileage and it's gonna wear hard on your driveline..

 

[Dszx13]

I searched an searched for something like this. Lol. I have a 93 k1500 ecsb. Put a 6" lift an 35s on. My trans recently went out out. Lost 3rd an 4th. Someone said maybe my gear ratio had something to do with it. So I decided my vin an I have 3.42s. I daily drive my truck an didnt notice a big difference in gas mileage. I don't tow much but I do every now an then. What would y'all recommend

 

[98slv]

4.88s is what I would do. If you're worrying about "taching out" then just slow down. Never good to tow anything too terribly fast. If your towing down a turnpike or a busy insterstate then yea 4.56s would allow you to keep the revs down, go faster to keep up with the traffic better and tow better than OE gearing. From my experience towing down a turnpike, i had to go faster than what I wanted to keep my tach above 2,000 which is where it liked it best, didn't want to downshift or go into lockup either, anything below that I was getting run over and that is just as unsafe as towing too fast.

 

[Dszx13]

No trailer interstate I run 80-85. That's just to keep from getting run over. I only tow in town or country back roads. I also pull my friends out when they get stuck. I don't mud ride unless I have to get to someone lol. So basically I want the power for when I need it. Since i put my lift on I don't interstate drive much. Mainly in town

 

[90droptop]

gear recommendations for a 99k2500 burban 3" body lift will be towing a rock crawler/ mud bogger regularly
454/4l80e current tires are LT285/75r16 (33")this is also my DD and most towing sessions will be 4-6 hours,


my calculations say 5.13s on 33s with OD at 65(who want to have a giant brick moving faster than that) puts RPM @2550 is that out of the ballpark for optimium crusing rpm?