Originally Posted by Bouncy
Google gear ratio/tire sizing. You will find some charts that show what your Stock tire/Stock axle ratio is now.
The chart then shows if you go to 35-36" tires and what gear ratio would equal the same driving experience.
No, they don't show what will give the "same driving experience", they only show what the rpms will be at a 1:1 final drive ratio (not in Overdrive) which can be extremely misleading to the novice.
For example, let's say you have 30" tires and are getting 2400 rpms at 70 mph. So you go to the charts find find that some certain ratio will give you 2400 rpms at 70 mph so you regear to that ratio. So you regear to that ratio & go drive it but within a few miles, you go WTF I don't have near the power I used to & can't figure out why because you're at the same exact rpms you had before when you had 30" tires.
What has happened is all this: 1) The Jeep has a suspension lift so it has more wind resistance because it sits up taller in the windstream. 2) The bigger tire's longer radius against the axle shaft means it has more leverage against the drivetrain so it's harder to turn. 3) The bigger tire weighs more & is harder to rotate, not to mention being harder to stop. 4) The bigger tire has more rolling resistance. 5) Your Jeep is more armored with skidplates etc. so it is heavier, not to mention the heavier tires again.
What you have to do is talk with someone with actual experience, you can't just rely on charts as way too many think they can. You have to regear so you end up with slightly higher rpms than you had with smaller tires to truly compensate for everything. The charts can be a guideline but they're not the end-all answer to what ratio to go with. It's best to ask someone who understands the whole thing & will take into account all that plus the transmission type. Especially since the charts never show rpms for once you're in overdrive. If you have a 5-speed transmission, for example, your engine will only show the same rpms as the chart gives when you're in 4th gear. So with any modern Jeep transmission, your highway rpms will always be significantly (!) lower than what the chart says it will be because all charts show their rpms with a 1:1 final drive ratio like 4th gear gives if you have a 5-speed.