Recommended tire size with 4.10 gears.,,,

[JRB4x4]

New to the group.....I recently added a 2 inch AEV spacer lift to my 2025 Mojave X. Looking to increase my tire size to 35 or 37 while keeping 4.10 gears. Any suggestions on tire size. What changes in performance can I expect in either one? If you can post a pic, that would be great.

I look forward to your suggestions.

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[DiehardTory]

You Decide.

 

[NC_Overland]

It’s kind of a loaded question because 33s are perfect for 4.10s and 4.56 matches the ratio for 35s and 4:88 for 37s. So if I had to choose between the two, I’d go with 35s on 4.56 because it’s closer to ideal and not too bad with 4.10s and the 8AT.

 

[JTGuy]

On 4.10s go no bigger than 35s. They will get you anywhere you need to go.

 

[Zachanadandy]

My mojave has been on 37s since 1,100 miles on the odometer with the stock 4.10s. It's at 45k now. Cruises 85mph no problem, no lack of acceleration vs my buddies on 4.88s, wheels fine, hauls fine, tows fine. The 1st gear in the 8 speed is so low it's the equivalent of 6.73 gears on a tj or early jk auto on the 4.10s already. I've hauled 1,800 lbs of pavers 70 miles including 20 miles of washboard dirt road. I've towed 8200lbs 600 miles including up a grade that gains 4k feet in 20 miles no problem. And it still wheels just fine. Pics of the paver load and the trailer.

 

[Jteakus]

315's

 

[XraytecH]

(New Tire Size x Stock Gear Ratio) ÷ Old Tire Size = New Gear Ratio

 

[Zachanadandy]

(New Tire Size x Stock Gear Ratio) ÷ Old Tire Size = New Gear Ratio

Assuming you want it to drive mostly the same. Here's the problem with that math though. JL sport/sahara going to 37s is 37x3.45/32=3.98...4.10s are perfect for 37s? But if it's a Rubicon JL/JT it's 37x4.10/33=4.59. 4.56 being the closest, but some argue to round up so you're at 4.88s. Almost like the 8 speed is perfectly happy and well suited for 37s anywhere from 4.10s to 4.88s because it's got plenty of 1st gear and 2 overdrives and can therefore be comfortably over or under geared compared to any of the 3, 4, or 5 speed autos that came before it. The silly thing about purely doing the math that way is that it says the rubicon needs more gearing to run the same tires despite it's 4-1 transfer case already having way more gearing than the others in low range. I wouldn't spend the money regearing costs to change from 4.10s to 4.56s, just not enough gain for the cost. That's why the mojave is still happily on it's 4.10s and 37s.

 

[Afternoon Spray]

(New Tire Size x Stock Gear Ratio) ÷ Old Tire Size = New Gear Ratio

Sorry to resurrect an old thread. Using his calculation of the tires that I want (255/85/17) based on the initial Sport's gearing, 35x3.73 divided by the stock 32s I get 4.079. Does that mean 35s on my stock Rubicon will drive identical to a base sport S/willys model on stock tires?

 

[Zachanadandy]

Sorry to resurrect an old thread. Using his calculation of the tires that I want (255/85/17) based on the initial Sport's gearing, 35x3.73 divided by the stock 32s I get 4.079. Does that mean 35s on my stock Rubicon will drive identical to a base sport S/willys model on stock tires?

Yes...sort of. Taller tires will handle slightly different. If they are a lot heavier that can make a difference in mpg and acceleration. Shift points and rpms at a given speed will be pretty spot on though.

 

[Afternoon Spray]

Yes...sort of. Taller tires will handle slightly different. If they are a lot heavier that can make a difference in mpg and acceleration. Shift points and rpms at a given speed will be pretty spot on though.

The 255/85/17 Mickey Thompson tires I want are only a couple pounds heavier than the stock 285/70/17 Falken Mud Tires my truck came with.

 

[Zachanadandy]

The 255/85/17 Mickey Thompson tires I want are only a couple pounds heavier than the stock 285/70/17 Falken Mud Tires my truck came with.

Should feel about the same then.

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