i have a stock 09 sport 2wd with a 4.0L motor, and 3.55 gears, i have put 2 inch shackles and did the pre-key mod so i am up 2 inches in the back, and about 3 in the front. I have the stock size tire (235/75R15) still on it and i am wanting to put a set of 31 inch bfg km2's on it and wondering who has 31s on stock 3.55 gears, and how bad it hurts your acceleration and power?

 

Don't know if this helps. Mine is a 09sport 2wd standard. just installed 31x10.5x15 last friday and i noticed a very small difference in acceleration but nothing major.. power is still there. Now if it's automatic it's another story. Here is a pic of it with new tires and cranked t-bars.(need to crank them a little more ...still sagging.)

 

ya, myne is an automatic, probably better to go with 30x9.50 15 then when warrantee is finished then i would budget for gears, and who knows what size tire i will go with, but your truck looks good, like that color. Are those tires the goodyear wrangler territories from canadian tire?? and how does that exhaust sound on your truck?

 

I'm running 31's with the stock 3.55 rear and a 4.0 automatic no problems, ran 30's for a year and I havn't noticed a difference between the two power or acceleration wise. I still out accelerate my nephew in his 2002 4.0 edge on 29's.

 

Thanks! i love my exhaust. Installed it when i bought the truck new.Still sounds the same with 22000km on it,happy i bought it. Yes those are territories from CT . Very happy bought those as well ! buy 3 get 1 free type of deal. Why wait to change you're tires? if im not mistaken they won't bother you if you change for bigger tires.? FX4's got 31's stock... anyways i changed mine regardless of the warranty.And going to get a 3" lift soon.

Don't forget to put some pics up !! we want to see it!

 

You'll be fine with 31's and 3.55's

 

i had 31s and 3.27s you will be fine

 

i have 31s and my gearing is 3.55 or something like that and its a v6 3sl0w automatic and it does need more rpms to speed up from when i had 235 75-15s. i just went threw my first tank and my mpg dropped 2 mpg it should go up cus that tank i had it running and idling and stuff but just thought i would let you know about the mpg drop

 

sounds good guys, now the decision i have is bfg km2, or goodyear mtr, probably the km2s, thanks for all the input.

 

^ or wrangler duratracs, my next set of tires. Just my two cents. Let's see them pics which ever way you go though!

 

i have a 05 4.0 with 3.55 gears and 31" tires. never noticed a decrease in power.