Hey guys how are you all..i recently got some 325/60 r18 procomp tires and ive noticed that my mpg is pretty poor,,,like 11mpg..ouch. also my power just doesnt really seem to be what it once was.im sure that having 325mm wide tires isnt helping the cause either, but do you guys think that diameter has that large of an effect? i mean the tires i have are only really about 2 inches taller then the stock ones, is that enough to where i need to regear??? If so, what gears would you recommend that i go with. and what kind of mpg could i expect??... by the way, how can i tell what kind of stock gears my truck came with???

p.s. how much is regearing for everything start to finish?

thanks alot guys

 

With those size tires, I would regear. Not sure if you knew this but your speedometer is also off now with the larger tires so that is throwing off your odometer which is causing you to get a bad gas mileage reading. Check out these links, they will help you decide where you want to be with your gears. Your axle code is on your door sticker and then you can look it up in your manual.

http://www.csgnetwork.com/speedocalibcalc.html

http://www.s-series.org/htm/calc/ratiotable.htm

Here is some axle codes...

19 – 3.55 Non-LS
18 – 3.08 Non-LS
H9 – 3.55 LS
B6 – 3.73 LS

 

If you have 3:73's I don't know that I would fork out the money for a regear but if you have 3:55's and plan on going larger I would look into it. I about had a heart attack when I looked at my odometer after my fist tank with my new 285's then I remember the tire effect not as bad as I thought.

 

If they are 2 inches taller than stock, I think I would swap the gears. I'm not really happy with the 3.73's and stock sized tires. I'd probably swap to a 4.10 or 4.30 gear set. I used to run 4.10's in my 5.0 stang as a daily driver, which had a 26" tall tire on it.

 

You didn't say if you had a 4x4 or 4x2, 5.4 or 4.6. If you have a 4x4 your looking for about $600 per axle installed, just gears, no limited slip or locker. I would opt for the 4.10's, depending on what rear end you have 4.30's aren't an option, although I wish it was. If you can't read your axle code then mark your tires and driveshaft and lift the truck, spin the tires and count the number of times the driveshaft spins, about 3.75 times is 3.73 if it's about 3.5 times then you have 3.55's. I know this is long, but I hope it helps.

 

Ok i just checked the gears and i have the 3.55. sorry that i forgot to add this, but it is a 4x4 5.4 V8....So im still allittle torn, i dont know what i should do....im also not sure if i could even fork over enbough money to get this done??? what do you guys think??