WXMAN, can you delve into the subject of MPG loss and give a little more detail?
Everything you read says that 10 lbs. of unsprung weight is the equivalent of adding 100 lbs. load into the back of the vehicle, in terms of fuel economy, power, and braking. I don't know if that math is correct or not... but that's the rule that is passed around on the Jeep forums all the time.
So, assuming that is true, I'm running 40 lbs. of additional unsprung weight by choosing Falkens over another brand of AT. That's like carrying 400 lbs. around in the back of the Jeep all the time as far as my gas gauge is concerned. That's a BIG deal.
On my daily routine, I was averaging 19.2 MPGs in bone stock form. With the Falkens I'm at 16.0 if I baby it...and 15.2 if I drive it like I want to on the same driving route to/from work and play on the weekends. The 4.88s didn't do anything for my mileage pro or con...they just help me hold overdrive on the highway now, but my mileage hasn't changed hardly at all due to the gears.
So, it appears that I lost 3-4 MPGs from the Falken tire upgrade. Now, if I went with a lighter AT tire of the exact same size..how much would I gain back? Probably not much...around 1 MPG probably. But every 1 MPG is worth $20/month to the average person...so choosing a different AT tire would pay for itself FAST.
For that reason (and the others I listed) I'm going to try the Nitto Terra Grappler. It's listed at 53 lbs. each and has great reviews. I already have one for my spare...and as my Falkens die I'll get more Nittos to replace them with.
If my JKU was a trail-only vehicle I'd have MTs on it. But since it's not I have to be conscious of efficiency and ride comfort in addition to trail prowess...and the Falken just isn't getting it done.