I have a 4.2 v6

3.55 gears

36" tires plan on 38's sometime.

i want 4.88 gears

my trucks max RPM's are 5400 before i float a piston.

With the specs ive shown will i be fine with 4.88's?

hopefully someone can help me.

 

No problem at all. You could run 4.88's with with stock tires all day long!! They aren't THAT low...... If you have a 5 speed....it would basically make your 5th gear the same ratio as your current 4th gear.

 

Yeah you'll be good, with a 1:1 ratio, 38" tires, and 4:88 gears your rpm should be around 2800 at 65mph. Keep in mind that's a 1:1 ratio, so if you have overdrive it should be around 1900-2000 rpm at 65mph.

 

i never really understood when to use overdrive, any help?

 

If you are referring to an automatic overdrive, you leave it in overdrive except when you are towing and let the thing think for itself.

 

ok thanks guys. i just know my truck has made it up to 4200 RPMS right before shifting and i dont want to mess anything up.

 

4200 rpm is nothing. It has a rev limiter, and the automatic is going to shift anyway before it hits that, regardless of whether you have it "locked" in a low gear or not. I wind my stick to at least 5000 when I'm in a hurry.

 

ok thanks im really sucky when it comes to gears, transmissions, and RPM's and what not.