I am new to the forum and right now I am running 325/60/20 Km2's on my 07 JKU. My question is whether I should go with 37x13.5R20 or stick with 35x12.5R20, Will I notice a change in drive ability or power? I have a Jklever Evo coil over suspension and has been re-geared to 5:13. It is time to get new tires and I am just wondering if it will be worth the price difference or I will need to do more mods

 

Motor and transmission will have something to do with how it performs. If you have a 2007-11 with automatic I would stay at the 35" size with your gearing. If manual transmission or running a 2012+ with the 3.6 either should be fine. Of course comments sense would tell you 35" tires are going perform better as far as acceleration/power goes.

 

I just put 37x13.5x17 mud grapplers on . my jeep has 4.10 with auto and 3.8 motor, to be honest not much difference than the 35's I had before..

 

I agree with Dirtman and stay with 35's with the 3.8 auto. Also you may want to look at going with 17" rims the cost difference in the tires may pay for the new rims and you'll have more sidewall to airdown. I'm running 37 x 12.50R17 KM2's and love them.

 

I knew the 37's will have a impact on acceleration. Just curious on how noticeable. My 07 is manual and with the 325/60/20 has no issues on or off road.

 

5.13 gears are a very good match for 37's with the manual. Should not be an issue off road or on the highway.

 

Hi. I didn't want to start a new thread so I found one that is kind of relevant.
I have a 2011 unlimited auto with 35s.
I am about to change gears and am not sure whether to go with 5.13 or 5.38
I will upgrade to 37s when my 35s are done. I have looked at the gearing charts and think that the 5.38 would be the best option but hope it is not to short as there seems to be so many people who are on those tire sizes with 4.10 4.88 and claim they have no issue.

 

What axles do you have? And from my research, it looks like 4.88 would be a good match for 37's with an auto. 5.38 seems to be a little much unless you don't drive on the highway or care about mpg.