Would I eventually do damage to transmission if I don't change gears with 35" tires

 

You wont do any damage just loss of power. I am running 35s with 373 and have zero issues

 

I have the 3.8. Would it be that significant loss of power?

 

What gears do you have?

 

Anything less than 4.10's will flat out suck with the auto and 3.8

 

Stock gears. That's what I've read that they will suck. Just wasn't sure if it would cause any damage

 

Super chips helped my 3.21 and six speed but yeah it's a little slow

 

What's typical cost on changing gears?

 

Stock gears could mean 3.21, 3.73, or 4.10 depending on the options you have on your JK. If you don't have access to the build sheet for it, you can lift a rear tire (leave the parking brake off and be sure to chock the other wheel!!!) and spin the wheel with the transmission in neutral. Count the number of times the driveshaft spins for each revolution of the wheel, and that's the gear ratio you have.

If you have an auto, anything but the 4.10's are gonna suck. And even then, the 4.10's aren't gonna be great. You can get by with the 3.73's if you live in a flat area, but you're not gonna be too happy about how slow your Jeep is.

If you have a stick, the 4.10's should be fine, the 3.73's should be mostly ok, and the 3.21's... well, you can make do with the 3.21's if you live in an area without hills, but don't plan on using 6th gear much.

 

Most shops here in So Cali do it for around 1 grand installed. Including Off Road Evolution.