Big reduction in gas mileage.....

....my '03 Tacoma (v6, extended cab, auto, 4X4) has recently been getting MUCH worse than normal gas mileage. While I have yet to "measure" the exact drop in mileage, I have noticed that on two highway trips that normally take me just over 1/4 tank are now taking me a solid 1/2 tank to complete.
I am a lead foot and have some oversized off road tires (32" Cooper STT's) hitting the pavement. They are inflated properly and checked before each trip.
Truck has 108k on the odometer and no known mechanical issues.

Any ideas on the sudden drop in mileage?

The mileage drop has just recently occurred in the last 3 months or so. I take these trips every few weeks or so and always have since I bought the truck new in 2003. The mileage has never been this bad.

Any ideas??

Thanks,
Rumsoaker

 

Welcome to TW, when was the last time you had a tune up? ( new plugs)

 

That's where I'd start!

 

Winter gas?

 

o2 sensor?

 

Winter gas-- im hoping. Mine has been doing the same thing