Okay so i have a 01 ram 1500 4x4 laramie. I want to put some 35's on it. i believe i have the 3.55 gears, will i screw anything up by putting that big of tire on? or should i just go with 33's?

 

Going to any size larger tire, without re-gearing, is going to put added strain on your trans. As these guys weren't the best from the factory....... That said, there ARE folks our there running 35's on the 3.55 gears. Due to the larger/heavier tires, don't expect much out of the hole performance...... General consensus is: 4:10s for 33's, 4.56 for 35's.

 

And 4.88's for 35" tires if you hardly ever go over about 60mph.

 

do yall think that 4.88's are good for 37's?

 

Considering that's the steepest you can get for your rear axle..... it's gonna have to be. Should be about right at any rate.

 

lol im askin cause im still gonna be doing a fair amount of highway driving with my rig, and i have a 1000 mile move coming up in april. and i was gonna wait till i got a set of 3/4 ton axles but it could be a few years untill then. any ideas on what kinda rpms ill be pushin at 70? oh yea sorry for the thread jack

 

The leverage of taller tires jacks with your overall ratio, effectively reducing it.. making getting it moving harder.. once its moving, it should help you... But...

Folks forget that rotations mass is x4.. five pounds of mass that rotates causes the equivalent of twenty pounds at the center of the rotation.. keeping that mass in motion takes energy.. for every pound extra you add to wheels and tires, you've effectively added four.. it adds up quick.

You can figure you're saving gas/energy by using larger tires on the highway, and the math concerning ratios will agree, but the math that everyone forgets, the weight, does not agree.. it will work you over..

4.56 @ 70mph for me is about 2200 rpm in fourth o/d with tc locked and 35".. iirc it was around 1800 w/ 3.92's with 33".. . its likely around 1600 w/33" and 3.55..

 

Somewhere there is a RPM chart. Size tires and gears. I can't find it though. Damn lol

OK, found the chart I was talking about. It's at the bottom of the page, but does not include 37" tires. http://www.go.jeep-xj.info/HowtoSpeedoGears.htm

 

^That post should be own thread in DIY section. It's good reference info.

 

with my 35's and 3.93's i ran around 1800 rpm in o/d with tcc lockup