If you use the tire size calculator at redrock4x4 you get this:Right now I have P235/75/R15 tires on my truck now, my friend has some tires that are 30x9.50r15. How close are they in size? Will it throw off my spedo alot? Please dont laugh cause I dont know anything about tire sizes.
When I dropped from 305's to 265's I noticed much better pulling power and it is much easier to turn at low speeds. Of course, you can change the gearing to improve pulling, but that is expensive with 4x4 since both diffs have to be the same ratio. When increasing tire sizes more than 3% the increased loading on the brakes is dangerous.One thing most do not consider is that bigger tires require more power at all speeds, present a larger profile to the wind at speed. They cost you in lost fuel mileage and more wear and tear on suspension parts but yes they do look cool!!