Let's sy I have 15 in rims nd 38's what gears would be ideal??? And if I geard it would I have to regear it to run smaller tires or what?

 

I would do 4.56 gears you wouldnt neccecary need to regear it if you got smaller tires just depends how small i ran 4.56 gears on my 35's the only thing about 4.56 is you cant go over 60. I switched from 4.56 to 3.73 with a clutch type posi. Remember you also need to upgrade your carrier if you want higher gears

 

i ran 373s with my 38s for years. i had a torquey engine so it worked fine. lower rpms for the highway especially if you dont have over drive. but ideally 4.56s are the norm. but you start running high numbered gears the teeth get smaller. ive known alot of people to strip out teeth running 38s. 9 years later im still running my 373s

 

had 2.73s with my 33s... blew the Ring and Pinion. Now I've got my 3.73s with 33s. Ya learn the hard way sometimes. Didn't know they were 2.73s until I was counting them as teeth were falling out of the hole in the bottom of the carrier.

Engine also factors in here. Assuming you have stock a 350, 4.56s would definitely be the best. 4.11s at the least, I've been told that anything above 33s you need 4.11s or higher.. also 14 bolt axle or higher, if you upgrade the gears might as well upgrade the axle too.

 

heck my first truck had 2.73s with 38s and a 305 engine. talk about a dog. in 4low when i got stuck i couldnt spin the tires half the time

 

man 273 with 38 thats risky business. personally i didnt like my 456 i mean if your soley going to be offroading rock crawling those are the gears you want but for highway driving 373 and an overdrive tranny is a dream with 35's. Best of luck to you...