soeedometer

You need to change the speedometer gear in the T-case. It's easy to do.
http://www.quadratec.com/jeep_knowledgebase/article-46.htm

Remember, until you replace it, the speed difference is a % of your total speed, so at 10 mph , you might be going 11, but at 55 you might be at 65. Faster you go , the greater the error .

That radar reading was probably correct, as well. The speedometer is around 17% off. So a reading of 55 actually does mean 65. To actually go 55, your speedometer will show 48. Hope that helps you a little until you get the gear replaced.

There should be a metal tag on your front axle.

here's how to change it
http://www.4x4xplor.com/speedo.html

If you cant see the stamp (sometimes its difficult to make out on a 19 year old axle) you can stop by a jeep dealer and they can run your vin and get your gear ratio.

Until you get it fixed, there are plenty of free speedo apps that are free to download on your smartphone. I have this one for my Android phone. It's spot on with the NUVI gps and also against my wife's car.

Quote from Captain_kitch

well I just checked and i have a 3.55 gear ratio, so should i still go for a 4.10 gear ratio or would a 3.90 ratio be better?

there are many gearing calculators out there.

I never thought of an ap for my speedometer. I'll have to look at that. What the hell is YONDER?

Hope you told your Pop before you posted about your ticket on here!

I ran the same tires and usually configured about a 10 mph difference once the spedometer hit 55/60 just using that a guestimate to keep myself in check and not overuse the skinny pedal . . .

Once you get used to adjusting it gets easier to remember and you won't see those flashing red & blues behind you, or when the motorcycle cops are running radar and just step out and wave you over downtown . . .

Quote from Kuntryboy816

Until you get it fixed, there are plenty of free speedo apps that are free to download on your smartphone. I have this one for my Android phone. It's spot on with the NUVI gps and also against my wife's car.

Beat me to it. I just used one to check mine when I replaced my gauge cluster.

Change the speedometer gear. Easy to do. Also DON'T forget to change the O'ring.

Assuming you have the automatic transmission, 4.10 gears would be the best choice (I don't know if 3.90 gears are even available for an XJ). But, if you plan on going to 35" tires later or do any towing, just get the 4.56 gears now. The auto transmission has a big overdrive so it'll actually match nicely with the 33s on the highway.

Quote from Captain_kitch

my shop teacher said i should stay away from anything bigger than a 4.10 bc the pinion is more likely to break

Your axles will usually break before your gears. 4:56 are fine, would agree above that the ring gear will get too thin.

Quote from Slimer

I never thought of an ap for my speedometer. I'll have to look at that. What the hell is YONDER?

It's an app that let's you find places for outdoor activities that have been posted by other users. You can look up all kinds of things from backpacking to rock climbing to kayaking. You can look locally or pretty much wherever you want to go..