Gears for 38s

[slowburb]

I run 2500 or so rpm at 70 with 33's and 4.56's.

 

[peyton4x4]

I'm also building a 383 stroker so I'm just kinda worried about this whole setup. That's why I'm here for your advice lol

 

[SkyHighColorado]

i forgot to mention I have not corrected my speedo. so my when my truck says its going 70 its actually about 65 in real life.

 

[Kyle97GMC]

5.13s would be pushing 2100 rpms at 70 which I will be doing for 60 miles a day

You're the man driving 60 miles a day on 38s. I cry about 200 miles a week on 35s lololol. I respect that a lot. I have always been told it's better to be over geared rather than under geared but with your highway driving I'd probably say 4.88s

 

[peyton4x4]

I guess I'll be going with 4.88s. I doubt it will be undergeared but if it is I'll have the 383 to help out some to

 

[99'Subourbon]

IMO, speaking from experience now - minimum I'd go with is 5.13s for 38s.
I turn 2350~ rpm going 75 with my 35s and 456s... And it feels like $hit.

 

[MDR-97-Z71]

I run 2500 or so rpm at 70 with 33's and 4.56's.

Some of these Rpm's make me wanna keep my 3.42 and not lift... Why so high?? I thought you could run 38's with 4.56 no problem? Or is that a 10 bolt thing? I didn't know differentials changed how everything worked


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[slowburb]

Some of these Rpm's make me wanna keep my 3.42 and not lift... Why so high?? I thought you could run 38's with 4.56 no problem? Or is that a 10 bolt thing? I didn't know differentials changed how everything worked


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I'm not sure what you're asking here. Any tire diameter change or gear swap changes final drive ratio, which changes engine rpm at a given rate of speed. The only way you'd catch me with 38's bolted to a 10 bolt is if I was actually trying to watch something break.

 

[MDR-97-Z71]

Sorry I just seen your post specifically and that sorta blew my mind, isn't 4.56 way more than you would need for 33's? Generally though for anyone else to answer I thought 4.56 was best for 36's to 38's? for example, look at Tristan's truck, he's running 40's with a 10 bolt and 4.56


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[slowburb]

A 4.30 gear brings 33" tires back close to the equivalent of stock 245's and 4.10 gears. I'm one step hotter than that, so when these Duratracs wear out (taking longer than I expected), I can put on a set of 35's and wind up around the equivalent of stock tire/4.10 gears.