Regarding fuel economy changes:
Great insight on gear ratios in this thread. MY 2011 JK standard 6 speed transmission with 3:21 gears ratio and I have (265[30"] 70 17) AT tires on right now and just added a 2.5 inch lift.
From what I gather if I wanted to go up to a 35" tire I should regear to at least 4.10.
MY 30" tires run about 2000 rpm at 70 mph, a 35" tire as the chart reads that my rpm would drop to 1800 rpm or maybe lower?
I don't do much highway driving so it may be okay? but would gas mileage go down?
I'm around 16 mpg avg. right now.
So as I hear a 33" from a tire store, may be the tallest I should go with to keep mpg the same and rpm's the same and not have to regear? Although I see here in the Forum 35" to 37" are the go to tire size.
Hopefully I can get some feedback from longtime members here or merchants.
Thank you in advance.
cost you fuel economy - not as much as 35s or 37s, but there's no magic threshold.
increase in tire diameter and/or weight will likely reduce fuel economy.
You may already see ~0.5 MPG reduction from your lift (increased wind resistance).
Performance gains will
cost you at the pump.
- I think that's in the Bible (First Octanes; 87-91 or something ).
Regarding tire sizes:
What limitations have you encountered with your current tire size?
What offroading do you do now - snow, mud, sand, rocks, potholes in mall parking lot?
What do you wish to gain by changing tire size?
I'd throw 35s on that 2.5" lift and regear to 4.88 - but you might hate that setup
My Jeep on 37s with 4.88s is great for my wheeling needs, but sucks as a "car".
Beware the slippery slope:
bigger tires will wear stuff out quicker, and they're far more likely to bend or break shit than 30" tires are. Along with the 35s and regearing, I'd gusset the front C's, sleeve or truss the front axle, seriously consider chromoly axle shafts, and be open to the idea of hydro assist steering. You can blow through 2-3 grand like <snaps fingers> that
. And that $2-3K is if you DIY - if you're paying for labor, God help you
My 2 door 6MT Rubicon did great stock on the factory 32s with factory 4.10 gearing
Lifting it 2.5" and running those 32s / factory rims on 1.5" Spidertrax spacers was good.
Ran 35s for years with the 4.10s and it was good, but 4.88s really put it back to "sporty".
Stepping up to 37s with the 4.88s wasn't a huge performance hit, but I'd love some 5.13s or 5.38s
NOTE: all of those^ modifications cost me fuel economy, and made it a shittier road trip vehicle.
If it's a daily driver, don't go over 35s without a damned good reason (performance, not looks).
If you want fuel economy & don't wheel it, get the smallest tire you think "looks badass"
So . . . the answers to your questions rely entirely on what you're trying to accomplish