As the title says, I'm looking for feedback from anyone who has made the switch. I currently have 285/65/18s (about 32.7") and looking to level my truck and put on 305/65/18s (33.7") when my tires wear out. I just feel like the bigger tires would be a pretty heavy load for the 3.55s and would probably reduce transmission life.

Anybody running 4.10s and a similar size tire? Did you see a noticeable increase in power? Fuel economy increase/decrease? Any other thoughts or opinions?

Thanks in advance guys.

 

Went from 3.55 to 4.30. Bottom end went up considerably, but probably not enough to justify the cost.

 

I went from 3:55 to 4:10, but I swapped out for 34" tires at the same time. I think mine is about the same as it was stock.

 

Thanks for the replies. I think I would be happy with a stock feel if I went to a 34" tire.. What kind of mileage are you guys getting city and highway?

 

Never understood why full size truck owners care about fuel mileage. If you did, you'd own a Prius...

 

I don't care about fuel mileage.. But fuel mileage is a good indicator of how hard your engine is working, and will show a lack of efficiency in the drivetrain pretty easily. I just want my engine and transmission to have less stress and longer life by gearing properly for the tire size I will be running, and I think hearing some fuel economy figures would be a pretty good snapshot of the overall benefits (or lack of) from the lower gears.

 

14.5 MPG's with mixed driving.

 

13.5 or 14 with mixed driving. I drive a new Focus for commuting these days. That thing rocks the MPGs!

 

14-14.5 is about what I'm getting now so it sounds like the 4.10s would put it back to a pretty good setup with 34s. Mainly just trying to convince myself not to get 34s unless I am going to regear too hear too many bad things about transmissions going out prematurely with stock gears and big tires..

 

If you use this simple formula you can calculate what gear you need for the tire size you are planning on running to maintain your current driveability.

(current gear x new tire size diameter) divided by old tire diameter = new gear ratio

or

(3.55 x 33.7) / 32.7 = 3.66

In your case, you don't need to change your gear for such a small jump in size, unless you plan on going bigger later on.

 

05red, you are correct that 33 to 34 is a small jump. But my truck is an XLT and only came with 31s originally.. I didn't feel that my current tires warranted a gear change, but I just feel like the next set (34s) may need some lower gears to offset the height/width/weight increase. I looked it up a while back on BF Goodrich's website, I think the 305s are going to be about 8 lbs heavier apiece than my 285s (and the 285s are heavy to begin with), so that, along with increased rolling resistance from wider tires, is what I'm trying to account for.

My brother has an f150 with the same tires as I do, but 3.73 gears and I can feel a noticeable difference the times I have ever driven it. So I'm hoping the 4.10s will be a good improvement over my current setup even with bigger tires.

 

I"m averaging 16mpg mixed driving with 35s and 4.56s

 

OK well if you redo the formula based on your original tire size vs. new you get (33.7 x 3.55) / 31 = 3.86 so 4.10's would be good for your setup.

 

Wow! Are you in a hilly area? I'm averaging 14mpg with 3.73s & 33s!

 

Central Alabama, so not really. I'm not sure how it's so good. That's according to my Gryphon CS, so I sure hope it's right