Hi i use my 96 cherokee for as my commuter and my toy . i currently run 33 12.5 and was wondering if swithching to 31 10.5 would give me bettter noticable gas mileage ! thanks

 

I am sure it would but it may depend on what your gear ratio is... what gear ratio are you running? What MPG are you getting now?

 

Welcome to CF! x2 on ^

 

i dont know the exact ratio but its a chrysler 8.25 rearend and the previous owner said he thinks its just the normal ratio that they come ..
as for mpg i have never figured it out but i get like 350km tops on a 80 litre tanks

 

Most common is 3.55

 

im going to say its prob 3.55 than most likely

 

If it is a manual then it would be 3.07. Also if the gear ratio is not corrected then your speedometer is probably off too. Which means the mileage you think you have gone is not correct. If you original tires were 29" (235/75/15) and your current tires are 33"s, when your speedo says you are going 50 mph... you are actually going 56 mph.

 

x2^ iv never replaced my speedo and im running 31's. its about 4mph off.

 

You need to track it with gps to see how far you can go each time with filling up to get accurate readings

 

Ok thank guys I will try getting a more accurate reading.

It's an auto so what gearing would most likely be in that?

 

I had 33" bighorns on my auto xjwhen I got it. I tbought it would help by puting 31" at's on it. It made no difference. I had the correct speedo gear each time. I'm still trying to figure out what is up with my gas mileage. I have a stock 5 speed xj that gets about 17 mpg and it has about 50,000more miles on it. My auto XJ has been very well taken care of and only mods are 703 injectors and 2.5" dynomax exhaust with no cat. Oh and its lifted 3".

Edit: I should have mentioned that my auto only gets about 12 mpg.

 

3.55