Power loss due to heavy tires?

wayoflife

Administrator
Staff member
So how far can ya go on a tank .. im on cooper discoverer stt ... 07 JK 2dr .. just want to compare

If you're asking because you somehow think a few extra lbs. per tire is going to make some kind of measureable difference, you'd be mistaken. I guarantee you that a lighter tire with an aggressive mud terrain like tread will get measurably LESS MPG than would a heavier tire with a smoother street like tread. It's called "rolling resistance" and the lack thereof will make more of a difference than weight.
 

geezz

Member
i should have read the whole thread .. i misunderstood the direction .. i noticed a difference in power response when i went to the 33 12.5 coopers .. just thought it was wider and tread grip
 

JayKay

Caught the Bug
What I already said, the 4.10's you have now should be fine. Being that there's no reason for you to install new gears, that's where I would start and then run them for a while. You'll know in a real hurry if they are doable or if you feel the need to regear. No point in spending money on something that you may not even need. That is of course, unless you just have money to burn and are looking for something to spend it on.

I'm running stock 3.73s in my '12 manual on 35s. For the minimal wheeling I do, it's just fine. As Eddie said, start with your 4.10s and see how it does, you may not need to do any regearing whatsoever. I only plan on regearing when the time comes that I NEED a front PR44.
 

JayKay

Caught the Bug
Yes i did. Jeep Hardrock with 4.10's. At some point I will probably re-gear. Just wondering if 4.88's will suffice?

I plan to go to 4.88s and 37s. With the highway driving my Jeep will still see after its paid off and becomes a spare vehicle. Plus the wheeling here in MO isn't "hard" enough for me to need 5.13s
 

SierraSilver

New member
So out of curiosity, when does re-gearing become a factor when considering longevity of the ring and pinion themselves? I also am running 4:10 on Nitto 33.5" but wish to go to 37" or bigger. Back a few years in the Dusy trail video where Moby broke the ring and pinon Eddie mentioned that he knew that would happen. So is the carrier and gears larger and stronger in a ProRock compared to a gussetted and trussed Dana 44? Mine isn't horribly gutless on the 3.8 (chipped, cold air) but I'm concerned that I will still break a few teeth even if I re-gear like Eddie's did with the same set up. I also can't seem to get better than 10 mpg in town, but 17mpg is common on the fwy.

Marty
 

matt1171

New member
The 3.6l engine and extra gear in the transmission make a huge difference. I just traded from a 2008 to 2012 and WOW!! With the 3.8 I had to go with 4.88s for my 35s. With the 3.6, the stock 4.10s still feel great and better than my 3.8 with 4.88s.

People start answering these questions and don't take into account the year model. Someone's experience with the 3.8 engine is really worthless info for someone with the 3.6.

Like Eddie said - you'll be just fine with 35s and the 4.10 gears. I love mine. I won't regear unless I move to 37s some day.
 

SierraSilver

New member
Apart from the original question of power loss with tire size, is there a sure risk of blowing out a 4:10 due to the larger tire size? I know plenty have, and many haven't but it still worries me.
 

MTG

Caught the Bug
The 3.6l engine and extra gear in the transmission make a huge difference. I just traded from a 2008 to 2012 and WOW!! With the 3.8 I had to go with 4.88s for my 35s. With the 3.6, the stock 4.10s still feel great and better than my 3.8 with 4.88s.

People start answering these questions and don't take into account the year model. Someone's experience with the 3.8 engine is really worthless info for someone with the 3.6.

Like Eddie said - you'll be just fine with 35s and the 4.10 gears. I love mine. I won't regear unless I move to 37s some day.

If I lived in fly over country I probably wouldn't even regear a 4.10 3.6 with 37s.
 
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