I have a 2017 F350 CCLB SRW 6.2 with 4.30 axel ratios with stock 18" wheels. I am thinking about getting an aftermarket set of 20" wheels with a set of 35" x 11.5" tires. Does anyone know what that would make my ratio comparable to?

 

Assuming you're starting with 275/70R18 A/T tires, their nominal diameter is 32.5", give or take. By switching to nominal 35" tires, the effective axle ratio will drop from 4.30 to (4.30 x 32.5/35) = 3.99.

HTH,
Jim / crewzer

 

You'll be golden I'm running 285/75 18s which come out just shy of 35s with the 4.30 gear set and kinda wish I woulda went 37s instead

 

35" It would come out to 4:07.36
37's would come out to 385.34
https://tiresize.com/gear-ratio-calculator/

 

So it should be somewhere between 4.1 and 3.99. Would think I would be ok with that. My last truck had 3.73's and that thing was a pooch! This is my work truck and a normal load for me is around 2500lbs of tools, fuel and DEF fluid in my tool boxes and auxiliary tanks. I pull skidloaders and a mini excavator at times, but not all the time. This truck is leaps and bounds nicer to drive than my 2011!! I don't want to loose the drive ability of this truck but it definitely needs bigger tires to fill the giant wheel wells!

 

I pull about the same as you but not daily, I stuck with the 18" because I like more sidewall showing and went with 295-70-18's 34.4" but the load range is 4080 Lbs which was also Important to me. Put me at 416.16. I couldn't see the 1/4" difference in height. Load range was more Important.

 

If I remember correctly the tires that I was looking at were 35's but when I looked in the specs they were actually 34.5" tall.

 

also look at the weight Important. I stayed at 56 Lbs per tire

 

I tow my CTL and mini excavator's too. I just chose to go back to the 295/70/18 in place of the 35/1250/20's I had been running. I just want to gain a little more back out of the 6.2. I too went with the Michelin Defender's which are a lighter 10 ply rated tire at 4080 lbs. I am very happy with the switch. The 295/70/18 is a great size that offers the high 4080lb load rating, and fills the wheel well especially with aftermarket wheels.

 

The Defenders are a great bang for the Buck