General Tire's too big for Taco?

My 1996 taco 2.7 4X4 has `General Ameritrac TR 265/75 15 are they too large for this truck? I mean does this size cause too much strain on engine? I assume they are not the original size for the truck. I have heard from the locals they are too big for the little 2.7 as the engine does seem to strain a bit. I have replaced the cat converter and it has increased the power. I was concerned if the speedo was off by much or MPG? I like the tires on it, but just curious if the are the best for it. I do enjoy taking it off road.

 

speedo is probably not off by much.

They 2.7 has plenty of power for them, my bother runs them on his 2.7 4 cycl.

 

Get some gears! It will make all the difference in the world