Between tire sizes need help

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webejeepin

Member
I've checked out the FAQ for newbies many times, looked at builds and used the search feature, but still find I need some advice from the experts

2016 JKR, auto, 4:10 gears is looking like will be in my near future.
DD 5 days a week to work, 120Km round trip a day, off road is nothing extream.

Firm decisions thus far; 2.5" lift, 17x9 wheels with 4.5" BS, full size spare, aftermarket steel bumbers, Mickey MTZs.

No desire to move to 37" tires nor flat fenders.
Don't really want to regear either.
No plans to tow anything, and things are pretty flat here, small hills

We're I hit the wall in my decision making process is 315 70R 17 or 305 65R17?!?!

Some potos/build I see with two doors have the roller skate look with the 305s

Will the 315's rob me of too much power, and be a noticable drop in MPG?

Is the difference is mounted height really not that great?

My background is with a 08 JKU, Auto, 3:73 and 33s. This came up quick on me so I'm studying fast to do this 2 door right the first time

Thanks
 
webejeepin said:
I've checked out the FAQ for newbies many times, looked at builds and used the search feature, but still find I need some advice from the experts

2016 JKR, auto, 4:10 gears is looking like will be in my near future.
DD 5 days a week to work, 120Km round trip a day, off road is nothing extream.

Firm decisions thus far; 2.5" lift, 17x9 wheels with 4.5" BS, full size spare, aftermarket steel bumbers, Mickey MTZs.

No desire to move to 37" tires nor flat fenders.
Don't really want to regear either.
No plans to tow anything, and things are pretty flat here, small hills

We're I hit the wall in my decision making process is 315 70R 17 or 305 65R17?!?!

Some potos/build I see with two doors have the roller skate look with the 305s

Will the 315's rob me of too much power, and be a noticable drop in MPG?

Is the difference is mounted height really not that great?

My background is with a 08 JKU, Auto, 3:73 and 33s. This came up quick on me so I'm studying fast to do this 2 door right the first time

Thanks
Click to expand...

I would go with the 33s for the fact that you have the auto and no plans of regearing.
 
With the setup you are wanting, id say a nice 33-35" tire would be good. I wouldnt go any smaller than a 295/70r17. I feel a 315/70 will be too much tire for your position IMO.
 
If you don't to much elevation changes and not an extreme off roader, I think you can go with 315"s, the drop in power and MPG is not that much!
 
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I'm running a set of 305s on my rubi with 4.10s. It's definitely livable. Don't know on the 315s.
 
I have a 2015 JKU Auto 4.10's and on 17x9 wheels, stock fenders with BFG Mud Terrain 35". No issues with 4.10's...drives and looks great.

IMG_0508.JPG
 
Thanks everyone for the feedback. I was down at my local tire shop today comparing the same tire in both sizes....dang it gotta sleep on it.....starting to hurt my head thinking it through
 
35s Would be an Easy Decision

After having run on 35s for over a year (JKUR - stick shift), I can't imagine going to the trails with less in the way of tires. People run 35s all of the time with a 3.73. This should be an even easier decision for you as you say you are getting a JKR (2 door?) which is quite a bit lighter than the JKU. A friend here in Albuquerque runs 37s on his JKR with a 4.10 and an auto tranny. It probably isn't ideal on the highway but he does great on the trails.
 
JoeB-JKURX said:
After having run on 35s for over a year (JKUR - stick shift), I can't imagine going to the trails with less in the way of tires. People run 35s all of the time with a 3.73. This should be an even easier decision for you as you say you are getting a JKR (2 door?) which is quite a bit lighter than the JKU. A friend here in Albuquerque runs 37s on his JKR with a 4.10 and an auto tranny. It probably isn't ideal on the highway but he does great on the trails.
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Thanks. Yes I'm building a 2 door Rubi, auto, 4:10
 
Rock in AZ JK and WJCO,

Thanks guys, seems my journey of learning never ends with Jeep stuff.

Just for giggles I just went out an measured my old tires, MT ATZ 33 x 11.5 x 17 or 285 70 17.....my actual tire height on the jeep with 29 PSI is 31.25".

Well, I'm blown away haha

So the 315's really are looking what I should do.
 
I'd run the 305 imo. I run a 35 on a jkur with 4.10 and manual trans. When I'm on the interstate and hit a small incline I'm down to 5th to maintain speed.
 
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