pingman77

I know its not ideal, but wondering if anyone is running this exact setup?
315/70/17 duratrac on 2013 jku auto with 3.21 gears. If so, your thoughts.

Gman*2007

Its doable for the time being, but you'll want to reprogram with a procal or tuner.

Invest2m4

This may not be helpful, but I just put those exact tires on my 2013 2-door, manual, 3.73 gears. I'd say I have the next most tolerable/ideal set-up next to Rubi gearing. That said, I'd say anything other than city driving would be a fairly bad experience for you. With the 3.6 engine, acceleration is fine. I didn't really notice a difference. Above 50 mph, that's when it starts to become very noticeable. 5th gear is a must for me going up even a slight hill at highway speed. I'd guess you'd rarely see overdrive.

pingman77

Thanks for the replies. I would definitely do procal. The reason im curious on this tire is a buddy is running 285/75/17 terra graps that weigh 56 pounds each on his 2013 jku. His is very tolerable at higway speeds with 3.21 gears. Now, the 315/70/17 duratracs are a little larger but only weigh 60 pounds each. Would there be that big off difference in performance?

Invest2m4

I think your question about performance depends on how you define it. It takes more power to move heavier tires that also have more friction from more aggressive tread and a larger contact patch. The HP/Torque curve of your motor doesn't change. Making numbers up, assume right now it takes 95 hp to move your Jeep at 60 mph and that 95 hp is made at 2000 RPM. Then say the larger tires need 110 hp to go that same speed and that 110 hp is made at 2400 RPM. In your case, you will probably run a lot in 4th gear on the highway to get at the right part of the engine curve. If you regear, then you could do the same in overdrive.

That is oversimplified, but just trying to illustrate. You will probably be a little sluggish right of the line, but not enough to care. Will you see overdrive a lot less? Yes, but that doesn't mean your performance suffers materially (it is really your Jeeps way of maintaining the needed performance).

I say go for it. Yeah, maybe a little less than ideal, but you'll forget about it the second you see how sweet the tires look on your Jeep!

pingman77

I really like the trail grappler look, but they are almost 20 pounds heavier per tire. The duractrac 315/ 70/17 is the lightest most aggressive tire I have found. I think im going to give it a try and if it doesnt work, ill probably trade in 14 for one with atleast 3.73 gears.

Invest2m4

You're only looking at maybe $1500 for a regear ($1000 at a couple places offering a deal). That is a lot cheaper than trading in for a 2014 just to get gearing that still isn't ideal. The only trade that I view as worth while, would be to a Rubicon. I have an ultra-light 2-door, and I still plan to regear from 3.73 (that decision was made after I put the Duratracs on).

pingman77

If I was to trade, it would be for a rubicon. My dealer is a personal friend and I bought the jeep with lift installed. He assures me no problem with lift conflicting warranty, but said a gear change by someone other tgan them is a different story. I would want 4.56 gears plus their rates are way north of $1500. So, im probably not going to try my luck on a gear swap.

cdubinbreck

Did you go through with it? I ordered the 315's (they'll be in on Monday) and I plan on regearing over the summer. I'm currently running the 285 Duratracs and have no problems whatsoever.

Stubicon

Not sure if you noticed but this thread is almost two years old. Doesn't look like the OPs been on in a while.