anyone have any idea if there's a major MPG difference between the 38x15.5s vs the 37x13.5s? the weight difference alone is about 10lbs per tire. anyone make a move from one size to another and notice a big difference? 90% of my driving is done on cruise control sitting at around 2k RPM and i'll be getting 4:56s right after the tires are put on.

 

It will pretty much go from bad to crap.

 

with 4.56 the 38 will have a slightly lower rpm but your year of ram wont accept a wheel smaller than 17 inches due to caliper size.

 

The difference in width alone is what will hurt you. Adding another 1" isn't too big of a deal, but as i stated before. 37" w/4:56's and you'll be very happy. The 13.5" tire will be easier to turn on pavement and will be much more forgivin on suspension components. You should really be looking into upgrading the shocks while your in there because the ride quailty is gonna suck with that heavy of a tire on your stock 2wd truck. Just my .02

I would stick with the 37" and 13.5" width. Any extra cash put towards shocks. Rancho 5000's are stiff enough to control those big tires.

 

your right dirty dog, had a rough start this morning and it didnt click he only put width, lol. i agree 37 would be better, you will need a 6 " lift though. good luck m8.

 

thanks you must have been who i asked about 38s before. i knew i asked someone but i cleaned out my PMs and couldnt remember what was said or who said it. sorry

as far as shocks i think i'll be getting the dual Fox shocks front and back. i think it's Fox that my suspension guy has set up for me, i dont remember. but i know they're dual gas shocks and suppose to be perfect for my setup. i'm looking at a 7" CST suspension lift and a 3" PA body lift with 20x10 RBP wheels with -40 offset and 37x13.5 Kumho MTs. those things i know for sure, but since i'm waiting for RBP to finish building my stuff i got time to change my tire size one last time. just didnt know if it would be worth it. i LOVE the look of the 38x15.5s but it seems i'll have to wait on those tires until my highway driving decreases alot more or i get something else for a highway driver.

 

Damn man, you havent got that thing lifted YET?? Youre slow and need to get to it.

 

lol nope not yet. its on the way though. i should be sitting pretty in about two more weeks. but it's been worth it for me to be patient

 

Tire size has bearing on the mileage but then again so does the the tread. Stock tires on my truck vs my mudding tires is 3mpg difference. Same tire diameter, 1" wider and the tread, ay caramba, way different. For your original question, the difference between the tires will be a little but I doubt more than a mile per gallon or two. I can't wait to see the pics of the finished job. My next step is to finish my wife's Jeep then she will let me finish my truck.

 

nice set up pirata, did you life it or just lvl it out( the rig in your sig)?