I own a 07 Unlimited x 4dr with the little pizza cutters 225/75/16 I believe. I'm moving to a 285/75/16 Will I need to regear? I did a search but it seems like everybody is going from 32's to 35's and I'm going from 30's (I think thats right anyway) to 33's I would look in my owners manual to find out what my gears are but I left it out one night after looking some stuff up and my dog ate it (yeah I know) Anyway I guess my questions are 1: will I need to regear, 2: how far off will I be MPH 3: does anyone know where I can get a new owners manual? the dealership wants to charge me 32 bucks! Thanks in advance.

 

You have auto or 6spd?

 

If you have an 07 with auto then you have the 4:10 gears and are good to go on the tires, even the 3.23 gears(I think that's what the lower end was this year) would probably be ok Your speedo will be off but your dealer can reflash it to 32 inch tires and there isn't much difference between 32's to 33's. I didnt reflash mine.

The owners manual can be viewed online for free at jeep.com, click on the owners tab.

I'm assumming you bought hit used, thats why you need a manual?

 

I have the auto, I wanted the 6 speed but the deal was too good to pass up.

 

I did buy it used. I've only had it about a month or so the dog killed the manual on day 2 though!

 

Then, as said above, you've got 4.10's and you'll be fine with 33's. You can have it reflashed if you are really picky about your speedo being perfect, but it's not that big of a deal.

 

any idea what the dealership is going to charge me to reflash it?

 

I went from a 265/75R17 to a 305/65R17; in essence a 32" to a 33"; and my speedo was almost dead on. I tested with a Garmin GPS unit. So, I would test before you worry about going to the dealer for a flash. If you have the 4.10's, which you likely do with an Auto X, you'll be fine with the gears... at least I'm fine with it anyway.

 

I just upgrade to 305/70/R16's from the same Pizza cutters you have. Those are in essence 33's , I don't have a GPS unit, but I drove by one of those speed rader things, and my speedo is about 4mph off. My speedo said 40MPH while the radar read 44. Don't know how exact that is, but hope it helps ya =)

 

Your gear ratio wouldn't be in the owners manual anyway, it'd be on the window sticker, otherwise, you could get a dealership parts depatment to look it up by your VIN.

An 07 Unlimited auto will have 4.10's, though.