stock suspension
 

How big of tires can I fit on a 97 ram 1500 318 4x4 and will it increases fuel milage like I'm thinking

I've got 305/70/16 on stock suspension but they do rub slightly at full lock, max without any rubbing is probably 285s.

Bigger tires will not increase your fuel mileage.

285/75/16 is about as large as you can go without the tire rubbing something. Larger tires will typically rob you of your current gas mileage.

re
 

I figured as low geared as the truck is as long as I don't jump off the line it would increase my wheel speed at a lower rpm

It will. But there is greater mass in the tire and takes more energy to roll. Great rolling restinace. Also you are raising the brick higher In the air and not hellping the aerodynamic aspect any lol

If you do better than 70% freeway driving, you *might* see a small improvement. Otherwise, ain't gonna happen, you will see economy drop.

Yep he's so right that's why I have a dakota with a 3.9 sips fuel not gulps like the 5.9 with 33s
But you can't cry about how much fuel it takes to drive if u drive a big truck

i have the same year, i put 295 on stock suspension and they rubbed really bad on the upper arm not even lock to lock. i 90 degree turn and they would rub. i had to buy 2 inch spacers. hub spacers are illegal in just about every state so this is not a permanent fix

Your signature states u have a 5 inch BDS lift why u useing a spacer your going to kill your hub bearings what offset is your wheels