Yes.
yes
Tire size has effect,also o2 sensors , carb jetting, fuel injector size,transmission kits ,rear gears.
Tires do not have oxygen sensors. They can have pressure sensors. The lack of pressure sensors would have no affect on fuel economy.
Gas mileage also went down and I just replaced o2 sensors.
Removing the sensors will have an effect, and the engine will run poorly or not at all. If you staight pipe after the cat converter and leave the sensors, you will probably be ok. There are o2 sensor simulators available aftermarket, though I dont have experience with them. Removing the cat may cause problems with emmissions inspections as well. If you do remove the sensors, and it runs ok, you will probably lose gas mileage and power, because the computer will get confused.
Have a mechanic check the O2 sensors. If one is out then the computer will give the engine too much gas. I have also seen some sensors go completely out and the check engine light does not come on.
yes
A bad O2 sensor can affect gas mileage. It is an emissions sensor, so when it goes bad, it does not reflect emissions performance on the car, which could cost a lot in gasoline.
I'm not sure about 40% but it WILL reduce gas mileage I'm not sure about 40% but it will for sure reduce your gas mileage. 40% does extremely high for just one O2 sensor
The gas engine has one before the catalytic converter.
All O2 sensors are threaded into the exhaust system at various points. Upstream O2 sensors are located before the catalytic converter(s) and downstream O2 sensors are located after the catalytic converter(s).
There are four o2 sensors on a montero sport.