I Have A 97 Scab 4wd Thats In Need Of Tires If I Was To Put 75 Series Tires On Instead Of The 70 Series And Was Able To Get A Narrower Tire But Close To The Same Overall Outside Diameter Could This Help The Mpg By Decreasing The Rolling Resistance.are Than Any Drawbacks To This Theory That Im Not Thinking Of Or Wont It Make Any Differance At All.

 

Very little to no difference. The contact patch area would be the same, just a different shape.