Bu3askoor

Hello all,
I have been reading this forum and was able to get to some conclusions with regards to tire size vs gear ratio. I just need some advice before going out and spending the money.

I have an automatic 2dr JK 2007 sahara which comes with 255/75/17 (32x10.04). I have installed so far K&N air intake and TF 2.5. I believe it comes with Dana 30 front and Dana 40 at the back (4.11 ratio) -- i hope this is correct info on my model.

I like to use the jeep for dune bashing. Desert driving relies a lot on keeping the momentum going which also in some ways mean higher rpm. I'd like to enhance the jeep performance in the desert and ran into the following dilemma after reviewing the JK gear ratio chart.

Should i go for smaller wider tires for better traction (and compromise on height) or simply regear to a 4.88 and keep the stock tires?

it seems to me that regearing is more bang for the buck performance wise.

i would appreciate some feedback on this.

frankie945

If you have the tow package you will have 4.1. If no tow package you will have 3.73 gears. On the 07 models.

If you go with 4.88 that will gear you down. Unless I'm reading this wrong you want to go up.

spinlock

I do a fair amount of desert driving myself so I understand your need to keep the revs up., but unfortunately open dunes are not as abundant in this corner of the planet
You definitely need the wide tires for flotation, a tall narrow tire will just dig until your running boards are buried in the sand.

Unless you are jumping your JK, the larger footprint of a wider tire will help you more.

Some of the benefits of tall tires are wheel protection, more sidewall flex on rocks, enhanced crawling and ability to approach and go over relatively larger objects (AMC Pacers ).
These will be of little use in dunes.

Depending on your other needs and budget, if you have 4.10s, I would go a 32-33x12.5-15 tire unless you are going to regear.

What tires and sizes are you considering?

Bu3askoor

Thank you frankie for your quick reply. How would moving from 4.1 to 4.88 gear me down? looking at the chart i would only assume moving to 4.88 will result in higher rpm and thus "gear up". unless i misunderstood the whole concept behind this

spinlock

It is a bit counter intuitive , moving to a larger numerical gear ratio such as 4.88 is considered going to lower gears.

You are increasing your engine rpm but maintaining the same differential and wheel rpm which is what you want to do to move into the preferred power band of the engine which is roughly 2000-3000 RPM.

seer1

This is assuming the transmission never shifts and that you never work the stick. Four high in first should serve you well. Go with 5.13's, you'll bog down less and have better performance on the road too. 4.88's are for six speeds.

spinlock

My point was assuming you are cruising at a relatively fixed speed where shifting should be minimized on a manual and an auto can sustain the OD.

That is usually the starting design point and then you bias towards crawling, performance or fuel economy.

IMO and others, as expressed in numerous threads in this forum, the 5.13s are a very good match for 35" tires and the auto.

I saw no mention of 35" tires, but maybe I missed it.

seer1

As pointed out by actual experience, 5.13's are an even better match for 33's. 32's (when looking at actual measurement) wouldn't be much different.

nangulator

X2, go with 5.13s with a auto trans

aldaman

Currently running 33s with 5.13 gearing....Seems like a perfect combination to me