hello, well i got 38" super swamper tires for my truck but i hear that my stock 3:55's wont turn them that good with my stock 518 or the 47rh thats going in sooner or later, so i guess im going to need gearing, now i dont know if 4:10's would be to good because the truck would have to rev higher on the highway and i wont see to good fuel milage or with the bigger tires would the truck still get up to some good speed? or could i got to 3:70 ish gearing and still turn the tires while having good highway speed? or will my stock 3:55's hold up fine if i upgraded to the 47rh tranny?

 

I think to really decide you have to ask yourself what will you do with the truck?

Something in the order of 4.10 sounds like a good ball park area and a balance between "low enough" to take some strain off the transmission, and high enough to still cruise at speed. I sure would invest in some well thought out cooling for the trans, and a quality torque converter/transmission build when you do it.

A gear ratio calculator and some research on actual tire diameter you plan to run, and you should be able to get an idea what you will need for gears.

NoRM

 

Excellent advice

 

Well thank you :-)

That said I am going to run the 4.56 gears that are in my crew Cab. I figure with 38" rubber, if for some reason I find the cruise rpm to be more than the engine likes...I will just put 42's on it LoL


NoRM