gear ratios related to tire size.

[82CJ7JEEP]

Can someone provide a simple formula for tire size as it relates to axel ratios? I have an 82 CJ7 with an AMC 360, I currently have a 4' suspension lift (leaf springs) and no body lift. The jeep is currently riding on 33X12.50's and as they are starting to wear out I would like to replace them with 35X13.50's. I will be getting new 15X10 rims. I have verified the current axel ratios are 4.10. Will I need to increase this to 4.56 or will the current ratio work? Thanks for the assistance, I greatly appreciate it.

 

[bobcat481]

4Lo.com :: Gear Ratio & Tire Size Chart

 

[Bounty__Hunter]

According to the chart your RPM's will drop about 155 with that jump in tire size, so you need to decide if you can run the engine comfortably in it's proper powerband at any given speed. Automatic transmissions help with this.

IMO the jump from 4.10 to 4.56 isn't enough of a change to justify the cost and time involved, for only a 155rpm change

 

[82CJ7JEEP]

Thank you both for the reply. It appears that I will be in the proper rpm range if I go up to 35's. Thanks again.

 

[Rubiconrich]

To run 35's you will need more then just a 4" lift. You will need a body lift
and or trimming.

 

[82CJ7JEEP]

Thanks Rich, There are some pics on my profile page. Take a look and see if it is a 4" or larger lift. I have had the jeep for 3 weeks now and was told they were 4" lift leafs on the jeep. There are new shackles on the front and rear which appear to maybe add 1 to 2 inches. As I am new to jeep I am not quite sure how to tell exactly how much lift the jeep has. It is riding on 33X12.5X15's now.