456 or 411s?

[PC250]

I did a search and there still seems to be major differecesof opinions with gears. Right now I have 38x15.5. This will probably be the biggest tires I get. With work I consistently haul a two thousand pound toolbox in the back of truck. I also put on huge miles, as in two thousand a month so long hauls happen often. What gears would you guys reccomend, or just keep my money with the 373s'?

[sbarbee54]

Well if it helps I run 39's with 4:56s I am a little on the high side for crusing RPMS. Not bad about 150 RPM over. If you are not hauling a trailer or towing much I would do 4:10's. I tow a toy hualer at least once a month so i went to the 4:56's and most of the towing is on windy rocky mountain roads. No matter either will be a great improvement,

[PC250]

right now I cruise at abou 1750ish doing 70mph. loaded with my toolbox I cruise 2100ish...

[Mr. Black]

Having owned several lifted trucks in the past, I would go with 4.56s for a 37-8" tire. Your drivetrain will thank you for it.

3.73 swap to 4.11 is a complete waste of time and funds IMO.

[atvrider93]

I would go with the 4.10s or 4.11s or whatever it is. mine turns 36s with 4.10s no problem

[PC250]

Originally Posted by Mr. Black

Having owned several lifted trucks in the past, I would go with 4.56s for a 37-8" tire. Your drivetrain will thank you for it.

3.73 swap to 4.11 is a complete waste of time and funds IMO.

Originally Posted by atvrider93

I would go with the 4.10s or 4.11s or whatever it is. mine turns 36s with 4.10s no problem

This is what I mean, there is not one defenitate answer

[Mr. Black]

Actually there is.

Google search "Gear Ratio Chart" and study it. Install a gear ratio that will match what the factory engineers set your RPM levels at and then all the other pieces will fall into place.

[Mr. Black]

Another thing people often overlook, you typically want to over shoot the gear ratio number just a little bit when you start talking tires over 35s as not only do you have to compensate for the gear difference but also the large rotational mass difference.

I've never done the math but a 285 17 combo vs a 38 tire 20" wheel combo has to be healthy chunk of weight.

[PC250]

Whatever's cheaper is what Im gonna go with I guess

[cartmanea]

Originally Posted by PC250

right now I cruise at abou 1750ish doing 70mph. loaded with my toolbox I cruise 2100ish...

I don't understand this statement. If you're running the same speed, the RPMs should be the same since you can't lock out OD on the TorqShift.

Don't forget about 4.30s. To keep the stock ratio with 38s, it works out to a 4.43 ratio, which doesn't exist. With the load you haul, I would lean towards the 4.56 gears to help out transmission life. However you run fairly fast on the highway and put on a lot of miles, so that would push me back down to 4.30s. 4.10s would be too tall and not worth the change.