Recommend re-gearing for 35" tires for JK Sport

justin mazzon

justin mazzon

Member
I have a '13 JK Sport with 33" A/T tires and am thinking of going up to 35" A/T tires (probably BFG KO2's). Since I have to drive a minimum of 200 miles to go off roading, gas mileage is becoming more important. What would be a good gear ratio to up-grade too for the best gas mileage and also have decent off road performance?
 
justin mazzon said:
I have a '13 JK Sport with 33" A/T tires and am thinking of going up to 35" A/T tires (probably BFG KO2's). Since I have to drive a minimum of 200 miles to go off roading, gas mileage is becoming more important. What would be a good gear ratio to up-grade too for the best gas mileage and also have decent off road performance?
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I would upgrade the front axle to a D44 before I put gearing in a D30 with 35's. If you must keep the D30, I wouldn't go past 4.88s
 
I did 4.88s for 37s, ko2s run small so if that’s definitely the tire you plan to run in a 35 I’d go 4.56 for sure
 
Same here, 35” and 4.88 my rpms were screaming at 70mph. If you are never going up to a 37” tire I would go 4:56. I’m a concervative driver if that means anything.


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justin mazzon said:
I have a '13 JK Sport with 33" A/T tires and am thinking of going up to 35" A/T tires (probably BFG KO2's). Since I have to drive a minimum of 200 miles to go off roading, gas mileage is becoming more important. What would be a good gear ratio to up-grade too for the best gas mileage and also have decent off road performance?
Click to expand...

I would say 4.56 or 4.88. The later will be a little low for 35’s but if the though of ever going to 37’s has crossed your mind then it will be a good ratio for 37’s. If 37’s are never in your plan then 4.56 will be good for you.
 
rockwell said:
Worth upgrading 4.10 to 4.56 on 35’s with a 3.6 auto? Never going bigger


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I would say stay at the stock 4.10 ratio. The very minimal gain you will see from going to a 4.56 is not worth the cost of having someone regear your axles for you.

If you were to ever go big tires then 35’s then it becomes a different story but as you said your not going bigger
 
Recommend re-gearing for 35" tires for JK Sport

I am running 35s with 3.73 gears with no issues. It has been fine on local trails (flat ass prairie) and the ones I have done in AZ (fairly tame so far by WAL standards).
Likely will go to 4.56 summer of 2020 as I become more adventurous in AZ but still have to drive from Winnipeg to Mesa each year.



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I would just try out 35s before regearing. I ran 37s with 4:10s which is close to 3:73 and 35s. It was a bit sluggish but was still street worthy. It would be preferable to save your money and invest in a D44 rather than dumping money into the D30 IMO. If you do regear and your concerned about mileage stick with 4:56.


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4.10 with 35s is not that bad. Unless you drive lots of mountain roads and are having a hard time keeping acceptable road speed than I wouldn't re gear at all. I absolutely wouldn't waste your money to go 4.56 as the gain will not be worth the money spent, and 4.88 is the max that I would go with a D30.


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Recommend re-gearing for 35" tires for JK Sport

I have 35s with my stock 3.73 ratio, little sluggish in the mountains but still fine on normal roads in town. I would have it regeared to 4.88 but I can’t find a place to do it below $2,500 nearby... in that case I’ll just save for a new axle set

*just saw your question about gas mileage... if you go up to 4.56 or 4.88, your mileage will be worse. I would just stick with stock ratio if your main concern is mileage
 
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