I'm running 35" tires with a Donahoe Racing 4.5" lift. My truck is a F250 Lariat, 6.4, CC, SB, SRW with 3.73's. My truck feels down on power and my city and towing mileage have suffered significantly (~8 in the city and ~7 towing 8k#). I've done all my research on re-gearing to either 4.10s or 4.30's, but before pulling the trigger wanted to hear from anyone that is running a larger tire and has re-geared.

Any input on how performance and gas mileage is post re-gear?

 

Mos def on the 4.30, I run that on my 1999 with 35 in BFG's A/T and 6 inch lift which is now going to get 37in SuperSwamper. The 4.30 feel great. I have the V10 and it sure makes it a real puller but sucks gas, passes everything but a gas station.

 

Thanks - I'm leaning towards the 4.30's.

 

I have a 250 crewcab 4x4 short bed 3.73 gears with 6" lift and 37.50 tires on 20x10" rims and have plenty of power and get around 12.5 city and 14 highway mpg.

 

depends on your driving habits. if u mix town and highway then 4.30 would be good. if u do more town then i would think about 4.56, my cousin ended up goin with 4.56 and he is really happy with his town mileage

 

Assuming your stock tires were 32 inches (just a guess), you need a 4.07 ratio (4.10 would be closest) to restore your truck to stock. Upgrade to a 4.30 ratio if you felt it was down a little on power before you upgraded the tires.

https://www.ford-trucks.com/calculat...e_sizes/a-er2/

 

i dont know what trany you guys have or motor i have a 97 f 250 with stock gears assume that they are 4:10 not really sure i run 37s and i am getting 18-21 mpg out of it all i have done is change the exhuast tat really helped and intake.. i do alot of high way driving during the week but still drive a lot of back roads around town and still always get at least 18mpg.. oh and i got a auto tranny so not sure if that makes any differents

 

I'm running 4.30's on mine. Couldn't be happier.

 

I am running 4.30 with 35" tires and it is great because you get the power back that you lost from going with larger tires. I didn't see much of an increase in the mileage after changing gears, but it is well worth it for the power increase!

4.10 gears won't give you enough difference from the 3.73's to make it worth the cost. If you do alot of towing with your truck you would probably be happier going with 4.56 for the extra towing power.

 

4.56's!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I run 37" tires and it is just a scosche below stock pulling. YOUR TRANSMISSION WILL LOVE YOU FOR IT. '04 F250 PSD 6.0

 

Thanks for all the posts. I appreciate the input. I'm going with the 4.30's. I'll update this thread after the gears are installed and I get some miles on them.