02Texas_Rattle

I just swapped out today my OEM 265/75R16s (camper pkg)
tires for some 285/75R16s BFG All-Terrains.......

My question is this. My door sticker says 245's, but the truck came from the factory with 265's. Do I really need to do anything for the trany/speedo? I realize the speedo will be a little off and doesn't bother me. I've read SOOOOO many posts on having the dealer change the tire size on my truck's computer or getting a Truespeed, etc......AND where Chrysler's tool just changes the speedo, and not the shift points.

Ive never worried about this in my Jeeps, as they were all
5speed manuals and could "manually" control any bogging,etc..

This auto is my first.

The reason I'm asking is I do notice the TC taking a little longer to lock up when driving on the street, under 50...Just don't want to fry a TC for a little bit bigger tire......I can be really conservative with the throttle and it will lock up normally ~ as it did with the 265's. I've got 3.55's and drive highway unloaded 50% of the time, city 45% and highway towing 5%. When I do pull, it is just a flat 4K# Jeep.

Is this a big deal? Should I even worry/waste my time?


Thanks for all your input and thoughts,
02Rattle

phox_mulder

I went from the factory 265's to 315's and decided to get a Superlift Truespeed.
(door sticker also says 245s)

My speedo difference was a bit more than yours is, and I just didn't want to have to think too much about how much faster I was going than the speedo said.
I also wanted to be able to figure mileage without any complicated percentages and such.

I don't think it's going to be that big of a deal as far as the tranny goes, so therefore not really worth it.

Your speedometer will be 3.7% slow (give or take)
It will say 60mph but you'll actually be going 62.2mph.
Not enough difference IMHO for the expendature of a correction device.

My change resulted in a 9.3% difference, too much for my puny mind to remember to factor in ,
so I justified the cost.

Just keep in mind that those 285's will start to look small again, and you'll be upping the size in no time ;D


phox

Srigs

I would keep the 265s on your truck due to the 3.55 rear.

Double check your spare tire for the true size from the factory. I had 265s on the truck when I bought it but the spare was 245s. I put 245s on and the tranny shifted much better. If it came from the factory with 265s, then you will be OK with the tranny.

Srigs 8)

phox_mulder

Oh, forgot to mention that I also have the 3.55 rear.
I did lose a bunch of power off the line, but that's easily fixable by adding some more fuel, which I plan to do soon.

Hindsight being 20/20, I would have got the 4.10 if I knew I was going to go with that big of a tire.


phox

y-knot

I changed to larger tires also, but never bothered to re-calibrate the speedo. It Isn't brain surgury, just a simple ratio formula. Mine ended up being a little over 10%, and that is very easy to remember. 60 mph is now 66 mph, dah. My other truck is 15% off, but that to isn't a big deal.

Marine

Mine also has the optional 265's, and there is no difference in speedo compared to my GPS.

Mike

amartinson

As marine said, 265's were the optional tires that were available for your truck from the factory. I believe they came standard on the SLT's. I have yet to see a door sticker that shows anything but the 245's. I looked on one of those "tire size calculators" before and I think the difference between the 265's and 285's is only about 3.6 percent rolling distance. I wouldn't think that would cause any problems even with 3.55 gears. I have not personally tried them though.

96DodgeCD

My 265-75R16's on the front just barely rub the fender wells while turning. Mine is a 4x4. How does a guy put on even bigger tires w/out increasing this problem? Glenn Denman.

richard

There is a reflash for some of the ECMs in our trucks which disables lockup until 50 mph.
This helps a great deal if you do a lot of towing.
Most trans shops know about this.
Pull out your airbox and get the number off your ECM and call around.
I Had 305's on my truck when I bought it, put on 285's.
After they wore out I put on 265's.
I did notice it shifted a little better every time I went down in size.
The only drawback is that I have 4:10's and yes it did gain a little rpm on the highway.
Not enough to be a problem though, I generally don't drive over 70mph anyways.

Rich

02Texas_Rattle

Just called NTB.

Taking the 285's back, getitng 265's

Think I'll be happier.......and the trany too.

BigBlue

I went from 265's to 305's and the only problem I have had is some lost power off the line (which the Comp MORE than made up for ;D) and a little more time for the TC to lockup. I have the 3.54 gear ratio. I'm getting 315/75/16's as soon as my current tires wear out. ;D My odometer is about 10% off. I could care less about my speed. I just flow with traffic.

02Texas_Rattle

Maybe I'm just oversensitive, but my truck
shifts now like a champ. TC locks up right on queue
and doesn't take as long to shift, no jerking or hesitation either....With the new BFG 265's.


Only bad part, I was going down I 10 and lost my front
Chrome hubcap! Saw it wiz across 8 lanes of traffic and didn't even hit a car! Bet that bugger is a little scratched up!Off to the hub cap store tomorrow
as the dealer wants $50.00 for it.....list was $43
and the used will be $25 unless you guys know of someplace
BETTER and cheaper?

Thanks to all for your help with my tire dilema.........

02Texas_Rattle

sap

I am also thinking about putting 285's on my 02 4x4 with 3.55s but after reading these threads I don't want to create trouble. If the dealer recalibrates the speedo will that reset the computer functions that rely on speed such as shifting and brakes????

AlpineRAM

I think that a changing tire size let's say 5% more circumference won't do much harm to the tranny- actually you can drive up a slope with these trucks too. If you change the vehicle speed sensor signal to have the speedo read right you make the tranny shift up much earlier. (Now it knows about the higher speed) So you will be lugging the engine a bit more and also the tranny.

AlpineRAM

20014x4

I've been running bfg's 285s for about 25000 miles now. great tires. still have over half life left. didn't notice any change with my truck performance. speedo change is so slight you probably wont notice it. But I want bigger tires now 8)