[oil pan 4]

Back in 2007 I went to a 2 inch taller, an 1 inch wider and over all much heavier tire and saw no change in fuel milage on the highway or city. If anything it went up.
I went from a P-metric to a load range C floatation size on a 15 inch rim.
Going to a taller tire dropped my rpms needed to maintain 65mph by about 50rpms.
Lower cruse RPMs with high inflation pressure is what saved me.
Now all I will put on the truck is 31x10.5R15 size tires.

On a 1 inch narrower tire in load range C it can mean the difference between 2300 pounds per tire and 2000lb tire. Thats a 1200lb difference.
With just me in my truck it weighs just under 6000lb with an near even 3000lb per axel. With a 9.5 inch tire I would be driving around 75% loaded, even with the truck empty.
Not good, I don't like to load them over 90% (in summer heat).
If I add 1000lb over an axel that maxes out the tires. Its not hard to do when towing a trailer.

10.5 inch tires on the other hand give a better margin of safty. They are only about 65% loaded when empty. That gives me 4600lb per axel to work with (1600lb per axel after you add the rest of the truck).
Now if I put an extra 1000lb over an axel I am running about 87% load. I like that.

I never thought about it till I over loaded the tires on my truck and had 2 blow outs pretty far from home. Not fun.