1 have a 2004 ram 1500 4x4 with a 3" body lift and a 6" suspension lift. can anyone tell me if i can fit 40x15.50x 20'' nitto mud grapplers on without rubbing anything.

 

Dunno about the tire clearance, but I do know that your transmission will hate you in the morning. Do you have the stock front end parts still, or did the lift provide heavier duty joints, etc? Also, what gearing do you currently have?

 

Depends on back spacing of your rims too. But stock gears and ifs aren't going to respond well at all.

 

Don't expect to tow anything larger than a kid's wagon, either. That much tire will kill your overall gear ratio.

 

Read my Sticky https://dodgeforum.com/forum/3rd-gen...dodge-ram.html
It still helps for width and backspacing regardless of your suspension upgrades. For a tire that is 1" wider, you need .5" less of backspacing.

With tires that wide, you would need a 3.75" backspacing at the minumum. That puts lots of stress being that offset on the hubs.
40" will hit the bumper I'd imagine and be so hard on your IFS front end components and suspension because they aren't made to rebound that size and weight of a tire set-up! Stock wheel/tire set-up is about 70lbs. Go putting on a tire and rim combo that doubles that and your looking at a very rough ride for your suspension components.

35-37" tires looks perfectly fine on a 6" suspension and 3" BL. I'd go 35 or 37 and stay under 13.5" for width and you won't have near as much trouble.

 

I bet it would look awesome though

 

Sure it would, but it would be a useless street queen with no ***** and no pick up speed with tire diameter like that!
I bet a Neon would beat him in a line up with tires like that, especially if he has 3:55's.....pffft

Not to mention the mpg's drop would be significant. I'd guess 2-3mpg loss.

 

If he had a 2wd he could do 4.88s and make that biotch move

 

You are seriously going to put 40" tires on an IFS truck? Take a look at your CV axles and then go and look at the solid front axle on an SFA truck and come back and tell me if you think those CV half shafts can support 40" tires.

35" max on an IFS if you are gonna use your truck as a truck, although some people get away with 37s, I've personally seen many a CV snap with 'em...