I gotta 95 wrangler with the 4 cyl. I'm wanting to put 33's on it , but i'm afraid it will kill what little power I have. 95% of my driving is up&down the interstate. any body got any first hand experience with this. If so ,how bad will it be,and/or any tips that really would give me any more power. thank ya'll

Prolly not a good idea.  the '92 YJ with 2.5 I'm familiar with has a tough time turning 30" rubber on the highway.  Flat, level gound is OK, but any rolling hills or the need to bust through the aero "bow wake" of a semi necessitates a downshift (or two!). 

Let's have some fun with math, shall we!!??  (all theoretical, you mileage may vary!)

First, figure a one-inch "squat" on your rear tires, thus 33 x .5 = 16.5 "no sidewall bulge" radius.  Subtract the one inch guesstimate, you get a 15.5 rolling radius.  Circumference = 2 x pi x radius, or 97.4 effective circumference (this WILL be different that a measured circumference, as it reflects the true "moment arm" of the tire when viewed as a lever).

one mile = 5,280 feet, or 63,360 inches.   63,360 / 97.4 says that the tire will roll 650.5 times in that mile.  at 60 mph, that's also 650.5 revolutions per minute.  Handy, huh?  Anyway, 650.5 x rear gears (4.10 for stock 2.5 Wrangler) gives you a driveshaft speed of 2,667 rpm.  In 5th gear (.85 overdrive), that puts your engine speed at 2,267 rpm.  This doesn't sound THAT bad, given that these engines seem to come to life around 3,000 ~ 3500 rpm, but once you figure in the phone boothesque aerodynamics of a Wrangler, seems to me you'd be putting yourself in a world of hurt. 

Heh.  i like this answer.  I'm going to store it away for future reference.

Did you take into account the velocity that the earth revolves around the sun?  Or how fast our solar system is moving through the galaxy?  Doesn't sound so bad then.

Pete

With the 2.5 Jeep, the rotational and orbital speeds of stellar bodies is irrelavent.

Were we talking 4.0 or 258, well that would require new calculator batteries and another day or two of computations.

Bob

BAD IDEA! My little 2.5L is really struggling just on 31's. It's not bad in town but any hill at or around 40 miles an hour I have to downshift into 3rd and rev it up. Just to get up the stinking hill at speed. Could be cause mine is an 82 and is kinda tired. (needs an overhaul badly) But it sucks. Freeway driving is almost impossible. Highways are inconcievable. So unless you are living in a desert with no hills then think about an engine swap.  

LMAO... I missed this one!  

I dont know about 33's but my fiances yj with 31's and the 2.5 does fine on the highway and the hills.?