Concequences of larger tires with stock gearing?

[yellocoyote]

I was having a conversation with the hubby the other day, and I'd like some other points of view before making a decision.

I'm toying with the idea of putting 265/75's on my KJ next year sometime as my BFG AT K/O's are going to be pretty well worn by then. With the recent "boost" in my lift, my 245/75's are looking a little on the small side.

In my understanding, if you go to a larger tire (say something like a Treadwright 265/75, E rated tire) it's common practice to regear to 4.10's. He seems to think that I wouldn't need to do this because I'm not an overly-aggressive driver - on road or off (I tend to be pretty easy on the accelerator when wheeling). Is he correct in his assumption?

I understand that the larger tires are more taxing on the differentials... so, if I opt not to regear, what kinds of things could I expect to happen?

 

[Atrus]

I don't think you'd HAVE to with that size....

...but you may experience worse gas mileage, decreased power, and increased possibility of breaking something IMO. Totally guessing on the third one.

 

[HoosierJeeper]

It would be more of a nice to have, something to do later.

With the 3.73's, you'd need to become a bit more aggressive with the throttle to get to do what it used to, at least in town and off road. Not much you can do with the highway.

 

[kjweston]

I have 3.73s with 265/75 Maxxis bighorn M/Ts. I also average 13.1-13.2 mpg if I stay under 2k rpm when accelerating.. I would say you can expect numbers around there. It definitely is slower on road and takes more to get going.. If re-gearing wasn't gonna cost me $1800+ I would do it in a heartbeat, but I plan to just get smaller wider tires in the future.

 

[Uncle Krusty]

Larger diameter tires will definitly effect the gas milage as you try to make up for the lost performance with more pedal in the city.

There is also the other side, in that more rolling mass (bigger tires) takes more brakes to stop. My 2006 has 4 wheel disc, which is great, but you may see quite a difference with your 2002, as I beleive those still had rear drum brakes. You can help the brakes with some engine breaking - if you have a manual transmission.

 

[yellocoyote]

I have 3.73s with 265/75 Maxxis bighorn M/Ts. I also average 13.1-13.2 mpg if I stay under 2k rpm when accelerating.. I would say you can expect numbers around there. It definitely is slower on road and takes more to get going.. If re-gearing wasn't gonna cost me $1800+ I would do it in a heartbeat, but I plan to just get smaller wider tires in the future.

This by itself makes me reconsider the larger size... instead, keep the size that I have with a larger tread depth/pattern might be a better option. I currently manage to pull about 17.5-18mpgs city driving, so I'm not certain that I want to sacrifce that for a larger tire. :-s

Thanks for the input, all. If you have other thoughts/experiences switching to the larger tire, please keep 'em coming.

 

[HoosierJeeper]

How about say a 265/70? Or a 255/75?

 

[tjkj2002]

This by itself makes me reconsider the larger size... instead, keep the size that I have with a larger tread depth/pattern might be a better option. I currently manage to pull about 17.5-18mpgs city driving, so I'm not certain that I want to sacrifce that for a larger tire. :-s

Thanks for the input, all. If you have other thoughts/experiences switching to the larger tire, please keep 'em coming.

Like I stated on LOST I gained 6mpg's when I went from 3.73's to 4.10's when I was running 265/75 MT/R's on steel rims.

 

[yellocoyote]

Regearing isn't really an option for me yet - can't afford that price tag. I wanted to be certain of the 'issues' if I went that route. Doubtful I will now.

Troy - that mpg jump is insane. I knew I would be burning more fuel, but didn't think that it would become quite so sluggish.

HJ - not sure about the other sizes yet. I'd like to have something a bit bigger in diameter than what I have now... as the 245/75's are looking a little on the small side.

 

[tjkj2002]

Regearing isn't really an option for me yet - can't afford that price tag. I wanted to be certain of the 'issues' if I went that route. Doubtful I will now.

Troy - that mpg jump is insane. I knew I would be burning more fuel, but didn't think that it would become quite so sluggish.

HJ - not sure about the other sizes yet. I'd like to have something a bit bigger in diameter than what I have now... as the 245/75's are looking a little on the small side.

The crazy thing I was in Ft Lewis WA(near Tacoma) so pretty much at sea level.Went from 8mpg's city and 14 highway to 13mpg's city and 20+ mpg's on the highway.Oh and I drive my KJ like I stole it,my 3.7 bounces off the rev limiter more times a day then you blink.


You want to see a uphill battle try fitting 35x13.50x15 Toyo's on your KJ,5.13's is not low enough though the 5 alloy rims I just mounted up today seem's much better then the steel rims I was running.

 

[Porkchop]

I am runing 265 75 16 Duratracks had the Dealer set the revs it helped with shifting and the speedos right on but still gave up a little on the mpgs. Not that bad.
I also turn the OD off at 3am when the snow has not been plowed off the roads

 

[Porkchop]

TJKJ do you think weight may have been a factor too in your mpgs?

 

[tjkj2002]

TJKJ do you think weight may have been a factor too in your mpgs?

No since I was about 400lbs or more heavier after the gear install.With the gear install I also added a ARB bumper with winch,full SkidRow skid plates(minus the gas tank skid),rock rails,and a whole host of other things.All the while I still was running the same 265/75 MT/R's on 16x8 steel rims.

 

[Porkchop]

Wow thats great I would have thought it would be the other way around
Like I always say gearing is everything

 

[tjkj2002]

Wow thats great I would have thought it would be the other way around
Like I always say gearing is everything

Well I started using premium gas at the same time also so that helped alot.

 

[blue_kjR417]

I figure with the decrease in power you'd probably become not so light on the throttle because you're gonna need more rpms to turn over the bigger tires.

 

[rockymountain]

I just went to BFG KMs and dropped 2 MPG. Was getting what you're getting 17.5 -18. now an even 16. You'll see them tomorrow. They are heavy and you notice a real change when you turn on the AC. Seems like a 4 ****** jumped in and took over. Without AC on though it is OK, just a little bit of power loss.

 

[boebr1]

I am going bigger on tires in about a week. possibly 235/85's I don't want to have my computer recalibrated because I want my speedometer to be more accurate. it reads 4mph over actual right now. it is my belief that it will read 1-2mph under acurate after big tires... i tend to drive below speed limit, so this will work perfect for me. So... I will no longer have the ability to figure out what my actual mileage is... not that i can even figure it out now since speedo and odometer are off (yes, i compared my odometer to my GPS and it reads incorrectly too, but it calculated out to 19.8 on last tank)... I guess I will base my increases or decreases on the fact that I am used to using a full tank of gas in two weeks.