Alpha_rico

sportster07 What was your original ratio? I have the stock 3.55's.

sportster07

I had stock 3.55's as well. I forgot to mention that I had a 4.6 though, not the 5.4. It didn't "add" any power but it made my truck feel stock again and it had the power to pass things on the highway again like before.

I say just go for the 4.10's, a friend of mine went with 4.56's and says his mileage wasn't as good as mine and he has a newer truck with a 4.6 but the same everything else. Then again, there's too many factors to bring into play but I was very happy with 4.10's. I've ran 4.10's on other applications as well and IMO they're the perfect application for a half ton on 35's. You don't lose any mileage but your truck feels like it did without the big tires again. My 4.6 had no problem lighting up 35's with 4.10's.

uzikaduzi

original tire size X new tire size divided by current ratio would give you a number that likely isn't made but returns it back to stock... but you have heavier and likely wider tires that take more power to spin... rounding up is the best bet and a one ratio change (like 3.73 to 4.10) is not worth the money IMO. if you had 3.55's and went up to 35's 4.10's should be perfect to get it to feel as close to stock as possible... but, like it was mentioned earlier, 3.55's in the 4.6l are kind of light so the difference in mileage between 4.10's and 4.56's isn't that drastic with 35's. I'd bet it's at most 2 mpg on the highway and likely less.

when people talk about the MPG changing with tire size (regardless of whether they re-geared or not, since the speed ring in the hub is sending the info to the speedo), be somewhat leery of their claims. you're milage will definitely change but if the speedo isn't re-calibrated to match the change, they have no idea what millage they are getting. taller tires without re-calibrating will show less actual miles driven on the odometer than they actually traveled for that tank so their mileage is actually better than what they are telling you.