I am looking to get a new set of tires for my f 150. Its a 300 i6 with a 2" lift and i wanted to know what you guys think would be better, 31s or 33?? Will my i6 have the power to spin 33" tires? I dont want my truck to be a dog when i switch tires. Thanks for the help guys.

 

And what final drive ratio do you have?
It makes all the difference

 

I'm not sure. how would i check that? its stock

 

This old thread might help you find your axle ratio:

https://www.f150online.com/forums/pr...implified.html

 

Thanks a lot man.

It looks like i have a 3.08 gear

 

Get 31s. or upgrade to 4.10s and get 33s.

 

thats what i was thinking. If i get 4.10s how do i get my speedo recalibrated?

 

That depends on the model year

 

i have a 96 f 150

 

On a 96, the speedo/odo ("PSOM") is programmable.
It uses the RABS sensor on the ring gear carrier for the speed signal meaning that it does not need to be reprogrammed for changes in axle ratio; it does however need to be reprogrammed for changes in tire size.

There are several links to the re-programming instructions on this board. Do a search for "PSOM" and "recalibration" or "recalibration constant" and you should find them. Do not play around with it until you get your final tire size since you only get 6 changes per module.

The whole trick is finding the right constant. When you actually get your tires mounted post up the size and brand/model and someone will help

 

Thanks for all the info man. I went with the duratrac 31s. I dont have the money to do the gears and i didnt want to go with the 33s and be down on power. I think it still looks pretty good wit the 31s.

 

For 31 x 10.50-15s Ford lists the calibration constant as 9.18.
Just FYI for the stock 235/75-15s it's 9.72
Until you re-calibrate, your speedo will read 5.9% low. At an indicated 61, you'll be doing 65

 

Thanks man. I appreciate the help