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40 inch tires? Need larger gears?

15K views 17 replies 11 participants last post by  graygoblin 
#1 ·
Trying to figure out if I put 40 inch tires on my truck with i need to change the gearing?? I have 3.92 gear ratio in there now.. I know i can do a 38X13.50 with no problem but I think i might want to go a little bigger.. Any ideas??
 
#9 ·
Yeah I was thinking of getting the lockers at the same time any suggestions on a locker to go with?? There are so many out there its hard to decide which one to get.. As far as labor goes I work at a dodge dealer so atleast i got the hook up here with service my buddy usually helps me out with the work..
 
#10 ·
With 40 inch tire, I'd probably run 4:88s or 5:13s.

I'm sorry to tell you this, but I don't believe your front IFS will take the pounding from such a heavy tire, especially off road. I'v seen two such rams litterally blow thier front diffs to bits with just a 36 inch while off roading, and they were both unlocked. You'll be twisting front CV axles up like pretzels. Both trucks have since converted to solid front axles.
On a street only truck, they might survive.

I would do some research in forums where guys do a LOT of off roading and regularly run BIG tires. I could name them but don't want to get in trouble.
 
#11 ·
With 40 inch tire, I'd probably run 4:88s or 5:13s.

I'm sorry to tell you this, but I don't believe your front IFS will take the pounding from such a heavy tire, especially off road. I'v seen two such rams litterally blow thier front diffs to bits with just a 36 inch while off roading, and they were both unlocked. You'll be twisting front CV axles up like pretzels. Both trucks have since converted to solid front axles.
On a street only truck, they might survive.

I would do some research in forums where guys do a LOT of off roading and regularly run BIG tires. I could name them but don't want to get in trouble.
couldn't agree more, i don't think the rear will hold up either. what type of locker do you want? i don't know what they offer for the 1500 but you can go arb air, ox cable, electric or maybe something like a detroit. you can do a spool, weld the gears or a cheaper lunch box style. i suggest selectable for the front though.
 
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