Bigger tires vs. re gearing?

[Mr.Wilson]

So I currently have 4.10 gears with 35” tires. Instead of spending $2,000+ on different gears. Doesn’t going up in tire size kind of re gear your vehicle? Or am I wrong?

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[Barnaby’sdad]

So I currently have 4.10 gears with 35” tires. Instead of spending $2,000+ on different gears. Doesn’t going up in tire size kind of re gear your vehicle? Or am I wrong?

If by “re-gear,” you mean “make your vehicle even more sluggish to accelerate due to the introduction of additional rotating mass,” then sure…it “kind of re-gears your vehicle.”

As is typical with lift and bigger tires feedback, you’re going to get mixed responses: 1. Folks that’s are running huge tires with 4.10 gears and don’t see an issue with it, and 2. Folks that immediately noticed performance degradation and changed out the gears. The best though is the folks that are somehow surprised by the drop in fuel economy.

My recommendation would be to stay with the 35’s unless you’re prepared to re-gear, but you do you. It’s possible that you could convince yourself that the even bigger tires aren’t an issue.

 

[Gvsukids]

So I currently have 4.10 gears with 35” tires. Instead of spending $2,000+ on different gears. Doesn’t going up in tire size kind of re gear your vehicle? Or am I wrong?

This would've been a great poll question.
Don't forget to calibrate your speedometer.

 

[jay21mojave]

That is the set up on my Mojave now.. you should measure your tire diameter before you reset your tire size.. the 35's on our rigs (both are 4.10) really measure 34" on 1 and 33.4" on the other tire.. with the PSI set as per a "Chalk Test" both at 27 psi COLD.

 

[WILDHOBO]

If by “re-gear,” you mean “make your vehicle even more sluggish to accelerate due to the introduction of additional rotating mass,” then sure…it “kind of re-gears your vehicle.”

As is typical with lift and bigger tires feedback, you’re going to get mixed responses: 1. Folks that’s are running huge tires with 4.10 gears and don’t see an issue with it, and 2. Folks that immediately noticed performance degradation and changed out the gears. The best though is the folks that are somehow surprised by the drop in fuel economy.

My recommendation would be to stay with the 35’s unless you’re prepared to re-gear, but you do you. It’s possible that you could convince yourself that the even bigger tires aren’t an issue.

And group 3. Those that knew it would be necessary, so re-geared when the tires went on. I promise we exist. To be fair, many of us learned that here.

 

[Sarge502]

I have 3.73 and I’m staying at 35s. I know my limits and am happy with that.

 

[bleda2002]

To actually answer your question, yes tire size changes your final drive ratio. The bigger the tire the lower the ratio thus lowering overall torque and acceleration. People regear when going up in size to make up for the lowered final ratio and transmit more torque to the wheels.

 

[WILDHOBO]

To actually answer your question, yes tire size changes your final drive ratio. The bigger the tire the lower the ratio thus lowering overall torque and acceleration. People regear when going up in size to make up for the lowered final ratio and transmit more torque to the wheels.

It doesn’t actually change your differential gear ratio. People have come up with calculations to help people understand what their effective ratio would be. Meaning running a larger tire will have an effect like running stock sized tires on lower gear ratios. The point is that larger tires make lower gear ratios less effective. Higher differential gear ratios like 4.88:1 or 5.13:1 are more effective at rotating larger mass tires with the same transfer case output ratio. Vehicles are designed with the stock tire size in mind, and are then sold with appropriate gear ratios for that setup. When we change that drastically, the gears need to change as well if we expect similar performance.

 

[WILDHOBO]

I have 3.73 and I’m staying at 35s. I know my limits and am happy with that.

Can’t argue with that. I just get frustrated when people tell members they don’t need to regear. Choosing not to when mounting 35’s, knowing a small performance hit will occur, is completely reasonable.

 

[Wheelin98TJ]

It doesn’t actually change your differential gear ratio. People have come up with calculations to help people understand what their effective ratio would be. Meaning running a larger tire will have an effect like running stock sized tires on lower gear ratios. The point is that larger tires make lower gear ratios less effective. Higher differential gear ratios like 4.88:1 or 5.13:1 are more effective at rotating larger mass tires with the same transfer case output ratio. Vehicles are designed with the stock tire size in mind, and are then sold with appropriate gear ratios for that setup. When we change that drastically, the gears need to change as well if we expect similar performance.

bleda2002 didn’t say it changed the differential gear ratio. Said it changed the final drive ratio.

 

[Mac]

Depends on your tolerance level, IMO 35s are as big as I would go with 4.10s and 33s with 3.73s before having to regear.

 

[WILDHOBO]

bleda2002 didn’t say it changed the differential gear ratio. Said it changed the final drive ratio.

I stand corrected. I read it wrong.

Edit: my statements were accurate to my knowledge, but @bleda2002 as also correct.

 

[Blackjeepjk]

Another great question that brings up debate and I see really good, accurate information from the previous posts.

I’m running 40’s with the stock 4.10 gears and stock housings. I will be the first to tell you that it is not optimal and was not part of my original build plan.
Plan was to try it for 1 week to decide for Myself what I really wanted. I felt that stock 4.10’s is a little too much for my liking on stock tires and didn’t want the same on my new build.
Wind the clock forward 6 months, 12k miles, I will go with 4.88’s when/if I make the change. Once again, not saying I have the optimal setup now but it also is very manageable for my driving both on highway and light wheeling. These 8 speed trannies are amazing, granted I primary use 5-7, lol.

 

[johnparjr]

35’s and 4.1 you are ok and don’t really need to re gear but if you go bigger then I would and I’m actually going to go from 35’s back down to 33 on my Mojave when these wear out

 

[Gren71]

TLDC
op: youve poked a hornets nest of opinions man. It does change the final drive ratio, but doesn’t necessarily “re gear” your truck. Just makes it less efficient at doing the basics, and more efficient and some specifics. Youve got a nice looking setup, but maybe looking at lighter or thinner or smaller or different tread tires would make more impact than a $2,000 regear.


I chose to go backwards and went back to a more stock size. Unless you need 35s you’re just peeing money away, IMO.

i link my worth it to go back thread here

https://www.jeepgladiatorforum.com/forum/threads/mpg-experiment.53810/

Its an incredibly common thing among forum members to bro out and go 35s/37s/40s right out the gate, and then pontificate on how optimal it is and how theyre happy. And then, months later…theyre often talking about re gearing after being unhappy with the power loss and all that goes with monster tires.

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