Question regarding going smaller tires for commuting

So this is for anyone that might be able to help.

I have to commute 120 miles a day for work everyday so my truck is killing me on gas.
What would happen if i got smaller tires for my truck?
Like the smaller sized ones that the 4banger 5 lugs have.

Would i need to recalibrate the speedometer or anything else?

Currently i have tires that are 265/70/17 and im due up for new tires.
My truck isnt a 4x4 so lowering it wont bother me.

I really reallyyy dont want to buy another car right now either.

 

1) Yes, your speedo goes out a bit anytime you change tire size. There are many calculators you can use to figure out the percentage difference, but it's as simple as figuring out the difference in the circumference of the tire. If a tire is 10% less distance around the tire, it has to turn 10% more times in order to travel the same amount of distance and that'll show up on the speedo.

2) I'm not sure if smaller tires are the answer. Narrower tires from a brand that designs them for fuel economy might be my first try. Narrower tires have less rolling resistance than fat short tires. P rated and thin ply tires will also help decrease rolling resistance which increases fuel economy.

Why not find a mid 90's beater Corolla or Civic for a few K and use that to commute? It'll cost you close to the same initial investment and unless insurance or registration/emissions is retarded in your area you will save more money in the long run.

 

A smaller diameter tire will increase you RPMs on the freeway. Have you thought keeping the same diameter and going with a narrower and lighter tire?

 

Ill consider anything at this point.
Where do i look for p rated tires?


And im in no financial position to buy another car right now unless i want to buy a total bucket and im not going to.
My truck is due for tires anyways, i have enough money set aside for that.

 

P-rated tires are stock on the Tacoma. Some guys switch to LT and some tire shops recommend it because they are tougher on wear. LT tires tend to have more plies, cost more, and aren't very fuel efficient.

 

Look at the posted weights, I went from 265 to 245 and gained a solid 2mpg. The real difference was the original tires weighed about 44lbs and the new ones weighed 34lbs.

 

Increasing gas mileage has a lot to do with weight as Darryle pointed out.. Getting the lighest tire possible, will be best, along with stock wheels..