New gears? Or a boost cooler?

[RoCkfiSh363]

Hey folks and Merry Christmas. My 05 doesn't like to run on the highway at 55 or faster. I have 38 inch swampers and the stock 3.73 gears. The truck shifts into high gear and the rpms drop and the EGTs go steadily from 800 to over a thousand til I have to hit the tow/Haul button and they drop back below 800 but the RPMs shoot up to over 2200. My Innovative tunes on the SCT are programmed with my stock gears and 38.2 inch tires but is it just too much for the programming alone? Should I step up to a 4.56 or 4.88 gear?? My next option I guess would be to get a Snow injection kit and just ice down the EGTs when it gets hot and doesn't wanna down shift. Anyhow, I appreciate all the responses and recommendations.

[gotta_gofast]

Gears!

It will ease the strain on the rest of your drivetrain.

[RoCkfiSh363]

[QUOTE=gotta_gofast;3410954]Gears!

It will ease the strain on the rest of your drivetrain.[/QUOTE

Thanks! What ratio would work better. 4.56 or 4.88? I don't tow very often.

[dhanna6powerstroke]

What was your stock tire size? Here is a chart.
http://www.alloyusa.com/gear-ratio-calculator/

[licenced2burn]

Tire & Gear Ratio Chart at Morris 4x4 Center

this chart is pretty accurate i know our final drive ratio in our trannys is higher then the chart predicts so the rpms it shows arent right but the gear ratio to tire size will still convert the same.

I would say 4.56 should keep about the same final drive ratio as stock tires with 3.73 gears. Just my .02c

[RoCkfiSh363]

Thanks for the chart. Looks like 4.56 will be the best bet. Not sure what my stock tire size was.

[windrunner408]

Yea I would recommend the 4.56s as well. You'll have a slightly lower mechanical advantage with the 38s and those gears as opposed to stock gears and stock tires due to the excess weight of the 38in tires but the drive ratio should be very close and the tuning should more than compensate for the lack of anything else.

[Karls03]

A 4.56 gear is what you want. Leave the stock speedo pick up on the differential and when you're done, you're speedo will be close to your gps MPH.

sent from a dumb guy with a smart phone

[ODAWG714]

456 gears!

[RoCkfiSh363]

Would 4.88 be too high? I might be able to get a set for a little cheaper from a guy I know.