2KXJJEEP

Im running 33x12.50x15 with the stock 3.55 gears and i want to change out the speedometer gear only $34.99 or should i save my money and regear it with 4.10's then change the speedometer gear?

SeriousOffroad

In order to get back to your stock performance level (max HP/Tq) you'll need to go to 4.56 gears.

Use the pull-downs on the following site and you can compare various gear ratios to stock gearing.
www.grimmjeeper.com

ericfx1984

I run 3.54 gears and an auto with 33" tall tires... I have to run in 3rd on the highway, mileage is fine on the highway... not so much in the city

VTJeep

going with the 4.56 is going to bring you closer (as stated) to stock ratio. so this is a good starting place. the jump from a 3.54 to a 4.10 is pretty nominal. a 4.88 might be a little overkill, but i think that boils down to opinion and intended driving; if you know your gonna be in deep mud, or anything that requires some oomph, then going with the 4.88 will give you all the oomph needed and will allow for bigger tires, if you do end up wanting bigger..
dont forget about low range, too! running 4.56 and low gear will serve you quite well!

EDIT- buddy with 33x12.50's on his wrangler w/ the 4.0 and 3.55's went to a 4.56 and is very happy- no more bogging on the highway and needing 3rd and a lot more low end power on trails...