Larger tires with 3.21 Axle?!?! need help

[navyjoe11]

Good evening everyone, new member and first time posting to the forum. I just bought a 2014 ram 1500 with 8 SPD tranny, only problem is I have 3.21 axle because the price was too good to pass up. Any thoughts on tire size wider or taller or should I just stay stock? Thanks for any help or guidance to possible previous posts.

 

[ItsMeKO3]

I have a 14 Ram with the 3.21's as well. I just put on a 2" level with new wheels and tires. I put on 315/70/17 Duratracs. They measure out to 34.4x12.4. I have no rubbing and I think it looks perfect. I've only had them on a couple days, so I haven't a lot of time to calculate my mpg loss, but I'm not that concerned about it. As far as power loss, I feel like its minimal. Even with new tires on the 3.21's it will still snap your neck back when you step on the skinny pedal. I don't do much towing, other than occasionally my in-laws 3500lb boat in the summer, so that wasn't much of a concern for me either. Some guys will say you can't do it on the 3.21's, but with bigger tires, the new 8 speed tranny really does a good job. Here is my thread with some pictures and the info on my setup:

http://www.ramforum.com/f40/new_guy_-_new_truck_-_new_level_w_wheels_tires-55208/

 

[Caldwell]

what do you want to do with the truck ?

The weight of larger tires is what is gonna hurt you. Personally with 3.21's I would just stay stock tire size, unless you don't mind paying more at the pump to have the larger tire you want.

 

[14RAM4X4]

I just went through this - I have 3.21s with the 8 speed also. I put 295/60r20 Nitto TeraGrapplers on. I love the look and only have a very slight rub at full lock.

I noticed about 2 mpg loss and the off the line feeling is a little sluggish. Before, I had to feather the pedal so not to chirp the tires from a dead stop. I LOVED this feeling. Now, I notice I have to use a lot more skinny pedal for the same off the line performance.

I'm going to order a HF InTune next month and hope the 87 tune helps.

 

[Buddy]

2mpg!! thats actually a bit for changing the tires, thats a bit of a downer.

 

[navyjoe11]

Thanks for the input guys, I will probably just stay stock for now and put some more aggressive looking tires like the Zeon LTZ's.

 

[jbr]

I think down the road I am going to replace stock 20" wheels (33" diameter) with either 17" or 18" wheels to gain some more side wall for going on the beach. I will probably go with a 34" diameter to gain 1" ground clearance. With the added weight at each corner I am going to lose 2-3 mpg.

Anyone know the weight of stock 20" wheels and tires. I think the tires come in at 44lbs per corner...... Correct me if I am wrong.

 

[14RAM4X4]

2mpg!! thats actually a bit for changing the tires, thats a bit of a downer.

Thanks for the input guys, I will probably just stay stock for now and put some more aggressive looking tires like the Zeon LTZ's.

I like the look, was hoping it wouldn't make such a difference in mpg. I am probably getting 0.4 - 0.6 mpg better, but since I don't have a programmer, I can't correct the computer for the tire size.

Also, I'm running Nitto TeraGrapplers. According to Nitto's website, the specs run a lot closer to a 35x12.50 than a 295/60r20. The site says they are 34.45"x12.36." So they are a bit larger than the normal 295/60r20. Also, they are heavier than a lot of tires out there the same size.

Another option is new wheels or spacers and running a 305/55r20 or 33x12.50r20. About the same diameter as stock, but wider.

 

[navyjoe11]

14RAM4x4 you raise another good point, will the weight of the wider tire on the 33x12.50 affect the shifts points in the tranny or have adverse affects just as getting a taller tire would.

 

[Caldwell]

^ Yes... Rotating Mass, and Rolling Resistance will be a factor in going with a WIDE 33'' tire. Its no different then going with a 35'' really. My factory tires were ( Wrangler HP's ) weighing in at 43 lbs each. Now the standard tire has changed to the Wrangler SR-A's...

275/60/20 - Goodyear Wrangler SR-A's = 40 lbs. Per Tire ( 33x10.8" )

305/55/20 - Goodyear Duratrac's = 62 lbs. Per Tire ( 33x12.5" )

22 lbs of additional weight per corner is gonna create extra work for the engine / transmission, and will also have a noticeable difference in steering feel. Your going to notice a drop in MPG no matter what. Now you can slightly help offset the the weight of a heavier tire, by going with a lighter weight rim. I chose **** Cepek DC-2's because I liked the look, but after I bought them I realized that they are a bit lighter then the oem 20x9 chrome clads. The clads weigh roughly 38 lbs each I believe. My DC-2's are 31.6 lbs each. Roughly 6.5 lbs lighter per corner. If we owned auto cross cars that would be huge savings, but we own trucks lol. It's nit picking alittle, but to some people it counts.

I wanted to go with a 305/55/20 tire awhile back, but I didnt want to tank my gas any more then is lol, and now im driving alot more highway to my new job. So I ended up going with 275/60/20 Nitto Terra Grapplers. They give my truck an aggressive look, and I like the new steering feel. The big selling point is the tire weight. They weigh 43 lbs each, same as my original Wrangler HP's.

Even sticking with the OEM tire size, you can still find heavier tires that will drop your MPG. The New BFG A/T KO2's weigh in at 59 lbs each !!!!! for a stock size tire ! Take into consideration Load Range as well.

 

[xrsman]

^ Yes... Rotating Mass, and Rolling Resistance will be a factor in going with a WIDE 33'' tire. Its no different then going with a 35'' really. My factory tires were ( Wrangler HP's ) weighing in at 43 lbs each. Now the standard tire has changed to the Wrangler SR-A's...

275/60/20 - Goodyear Wrangler SR-A's = 40 lbs. Per Tire ( 33x10.8" )

305/55/20 - Goodyear Duratrac's = 62 lbs. Per Tire ( 33x12.5" )

22 lbs of additional weight per corner is gonna create extra work for the engine / transmission, and will also have a noticeable difference in steering feel. Your going to notice a drop in MPG no matter what. Now you can slightly help offset the the weight of a heavier tire, by going with a lighter weight rim. I chose **** Cepek DC-2's because I liked the look, but after I bought them I realized that they are a bit lighter then the oem 20x9 chrome clads. The clads weigh roughly 38 lbs each I believe. My DC-2's are 31.6 lbs each. Roughly 6.5 lbs lighter per corner. If we owned auto cross cars that would be huge savings, but we own trucks lol. It's nit picking alittle, but to some people it counts.

I wanted to go with a 305/55/20 tire awhile back, but I didnt want to tank my gas any more then is lol, and now im driving alot more highway to my new job. So I ended up going with 275/60/20 Nitto Terra Grapplers. They give my truck an aggressive look, and I like the new steering feel. The big selling point is the tire weight. They weigh 43 lbs each, same as my original Wrangler HP's.

Even sticking with the OEM tire size, you can still find heavier tires that will drop your MPG. The New BFG A/T KO2's weigh in at 59 lbs each !!!!! for a stock size tire ! Take into consideration Load Range as well.

Here's a question:

Say I put 35' duratracs on. 325/60/20 Duratracs weigh 67 lbs per tire. That would be 108 extra pounds total. Would the mpg loss be the equivalent of having an extra 108 lbs in the truck with the normal tires? Or because it's the rotating mass it will be more substantial?

 

[Caldwell]

108 lbs in the bed is nothing.

108 lbs of rotating mass will have a significant effect on power / mpg.