nwilliams98

Hi,<br>I was wondering if anyone has put larger tires on a truck with 4.10 gears. I currently have 265/75-16 tires but was thinking of 285/75-16. Has anyone done this? What did it do to your mileage? ( I realize you have to do some calculation for the change in speedo and odo). <br><br>Also, I bought my truck used. Its a 4X4 4.10 97' 2500 laramie slt. Did it come from the factory with 265's or 245's like the door says? <br>Thanks in advance.<br>Nate

truckkiller

it really depends on what your going to do with your truck. I have a 99 and my 315/70/16 dont rub. my friend paul has the same year and style (his is an slt mine in a st) and his 305/70/16 will just about clear. 245's were the standard tire in 97 (i think. i know they were in 99) and the upgraded rims gave you the 265's you have. you didn't say if its an auto or not but with the 5 speed i picked up a little mileage. good luck with your new truck. ;D

j

you're only going up in size by one size (about 3/4 of an inch. your mileage may increase slightly with those gears. i have 4.10's in mine and it seems to almost need bigger tires as it seems to be geared too low. i will be going with 295/75's next set, but i also have a leveling kit. not sure if the 295's will fit stock hight (295's are 34.3 inches tall.) i also am installing 4&quot; exhaust and an edge comp to make up for any lost power (and then some)

Den052

Should be no problem to change sizes. You will probably notice a mileage increase. Personally myself I look for mileage in a diesel. I would like to see a 3.08 or 3.40 rear end in my Dodge. Unless you are pulling railroad cars, you don't need anything over 4.00. If the overdrive is too low when pulling fifth wheels or trailers (etc.) then drop the automatic out of overdrive to pull loads ocasionally. With the proper ratio rear end, I could see getting 30 mpg out of a Cummins Dodge pickup empty, and still be able to pull medium to heavy loads from time to time by not using overdrive.

wooff

I don't have the 4:10 gears but i went from a 265/75 16 to<br>315/75 16 BFG AT KO and they rub a bit when you have the steering wheel hard over and mpg did drop a bit but it's worth it for the look they give. so with 285's i can't see it dropping that much.

Den052

Mileage probably dropped because of the wider tire on the road. Anytime you can slow the engine down at 70 mph you usually up the fuel mileage. Myself I would like to see a cruising gear added to all vehicles. Once you obtain say 70 mph and are traveling at that speed for a long time, slow the engine down for max mileage. One thing I couldn't understand:<br>The engineers at GM spec out a average Gm 1/2 ton pickup with a 2.78 rear end with a 3 speed transmission. If you opt for the &quot;overdrive&quot; then you get a 3.08 rear end with a 4 speed overdrive transmission. My feeling is &quot;leave the rear end alone&quot;, I can select what gear I want in case I decide to pull something.!!!!!<br><br>

GScott

My 99' came with the stock 245's. I use my truck as a daily driver (mixed highway &amp; town driving) and to tow my 7k, 25' boat. Auto, 4.10 gears, 72k miles on the truck.<br><br>Replaced the original boots @ 40k with Mich M/S 285/75's but had to upgrade to &quot;E&quot; rated sidewalls for towing. Work great with no real noticeable difference in mpg.<br><br>Highway mileage empty - 19.7<br>Highway mileage towing - 15.5 - 16.<br><br>Of course everything depends on the quality of fuel and topology of road trip. I always carry fuel treatment for those special times when I pay top dollar and get lousy fuel. With the on-board mpg computer it's easy to tell when to add the fuel treatment.

richard

I am currently running 285/75/16 Coopers on my 97 with an automatic and 4:10 gears. I did not notice any change in mileage or power. When I purchased the truck, it had 305/70/16s on it.I have even towed with both size tires and it still made no difference to speak of, maybe 1-2 mpg which could be from more than just the tires. This all took place in a three to four week timeframe when some stations had switced to winter blend fuel,me sliding the fuel plate,etc. So don't be afraid about larger tires, the cummins is too much of a powerhouse to let tire size variables in normal driving conditions take away from the fuel mileage. If you plan to tow a 15,000lb trailer through the mountains on a daily basis, then it would be something to worry about.<br>Hope this helps,<br>Rich ;D

John_P

nwilliams98:<br><br>Welcome to the website!<br><br>I have a 96' Dodge CTD and changed to B.F. Goodrich<br>Radial A/T's (285/75R/16) shortly after I bought it.<br>The 285's don't rub at all, but 295's and 305's did.<br><br>The larger tires will cause your speedometer to be<br>off. All you have to do is find out how much (you<br>can do this on the Interstate by the M.P. markers)<br>and then go to your local Dodge dealer. They have<br>several different &quot;gears&quot; they can change out for<br>you to get the speedo/odometer back to where<br>it should be! We are lucky to be able to do this<br>on our older 12 valves, as the newer 24 valves <br>do not have this because of the electronics etc!<br><br>Good luck!<br><br>--------<br>John_P <br><br>

redram95

I'm running 285/75/16 cooper AT. Only thing I've noticed is lack of power on hill climbs while towing. Believe I have 3.54 gears. ??? Question for everyone what brands are you running. I can't seem to keep tires on the rig longer than 14k. although Cooper keeps pro-rating them for me so that is good. ;D

quantrill88

i have 285/75/r16 super swamper trxus', not big change at all and fit great...

shortround

I'm running Kelly Springfield 285/75/16's. Didn't notice any power change and highway mileage actually went up. Your spedometer will be about 3.5 % off. Got plenty of clearance.

dodgeman01

[quote author=redram95 link=board=5;threadid=7116;start=0#87873 date=1041614374]<br>I'm running 285/75/16 cooper AT. Only thing I've noticed is lack of power on hill climbs while towing. Believe I have 3.54 gears. ??? Question for everyone what brands are you running. I can't seem to keep tires on the rig longer than 14k. although Cooper keeps pro-rating them for me so that is good. ;D<br>[/quote]<br>Yea I seem to have the same problem. I ran 315/75/16 wild countryes. They cost 115.00 a piece. ran them for 4 years and got a avg of 20k and a high of 35k on them. I just bought a set of BFG's 31575r16 and they seem to be doing alright. It is not woth the moneey I paid for them. 178.00 a piece. thats just too much. for my to rectify buying those tires thay better last 60k at least.<br>DM01

DF5152

here is a link to an excel document i made up it has MPH, RPMS in relation to tire size changes and gear ratio changes. The ratios are for PSD with a standard shift You can get the idea althought the RPMS will be off a little. If someone wants to send me the ratios for the Dodge for both manuals and autos I will make a new chart and post it. Hope this helps. I will also post a link to my current truck which has some of the recent mods I have done. This truck is FOR SALE if anyone is interested. The new DOdge is on its way.
Dan
Gear Ratio VS Tire sizes
My Cheby and some mods
Truck for sale
Here Is a tire chart I made Too

Hope some of this helps.

Dan

Pete Miller

I went to 285/75/16-Ds on my 96 4WD CTD with 4:10 gears. The bigger tires allow me to go off road with less jarring due to the lower air pressure (65 max) while carrying the same load. I do not believe you can get bigger than 285s into the spare tire well. The 4:10 was to low for my needs anyway. I love the result of the tire conversion.