I've been doing a lot of searching before putting out our the money for wheels, tires and gears before I know that it will all work out ok. I have the ATS X and C springs which although I never actually measured before and after I believe I got close to 3 inches front and rear. Before I decide on gearing I want to be sure of the tire size/wheel offset I'm going with. I would like to run 20x9.5 wheels with a -18mm offset. The tires I've been looking at are the 275/65R20, 35x12.5x20 and the 325/60R20. Currently I have 285/75R16 tires on the stock wheels. Is there a good way for me to determine whether or not I will have interference issues with the new tires and wheel mentioned above? I'm not sure how much impact would be caused by the little bit of negative offset either. Aso far as gearing, once I nail down the tire size I would like to get as close to an effective ratio of 4.30 compared to stock as possible. Since it is my DD as well as my TV I would still like to be able to maintain 65-70 on a level highway at a decent rpm (2200-2400??). Just not sure what I would be running if my combo works,out to an effective 4.40 or 4.50. Thanks for any input you can provide.

 

I cant help much with gear ratio but I can with tire size. I have the ATS V/C kit with 2008 20" Lariat wheels. I have 2" spacers. I originally has 35x12.5X20 tires. The looked great but I did have inner fender rub at full turn left or right. I tied back the inner fenders but still had a good amount of rub at full turn. My 2nd set of tires are 275/65R20. I have just a tiny bit of inner fender rub only at full left turn. I do not have my inners tied back at all. I would imagine if I tied the drivers side back a bit it would solve the rub problem. Perhaps with the X/C it may be enough to allow use of the 35" tires without rubbing. Good Luck.

 

Aftermarket wheel backspacing and offsets are a mystery to me, so no help on that question, sorry.
I run OEM X codes with an additional leaf added for a 3 7/8" lift over stock and I run 305/70R18 Nitto Dura at 35.28"X12.8" on OEM '04 Lariat 18"X8" wheels. I pulled my plastic inner fender liners back with a couple of cable ties to avoid them rubbing and now only have a little bit of tire on spring rub at full steering lock. I do plan to add the steering stops at some point but for now I just back off the wheel a hair to stop the rubbing when at high turning angles.
I've run a few different tire/gear combos and have some RPM data for some of those.

Speed...........32"/4.88.............35"/4.88
55.................2075RPM...........1900RPM
60.................2280RPM............2055RPM
65.................2430RPM............2230RPM
70.................2600RPM............2400RPM

As you can see the 35"/4.88 combo meets your 2200/2400RPM at 65/70MPH goals perfectly. My 35.28" and 4.88 gear combo nets an effective ratio of 4.39, very close to the factory option of the sweet spot 4.30 ratio. Changing the gears from the factory 3.73 was the single biggest performance enhancer that I've done to my tow rig EX, it's like a completely different truck. The unloaded mileage has gone from an all stock 31.6" tire 3.73 ratio no lift 14 MPG in my daily 50/50 mix driving to a current 12.5 MPG at 65 MPH on the Interstate, some of the drop is due to the lift and tires as well as the deeper gears. But I only use the EX as a tow rig now with virtually no daily type use. It's towing MPGs went from an all stock 6 to 7 MPG pulling a 9500lb TH to a solid 9 MPG dragging the same trailer at the same weight and speeds over the same route with the gear change to 4.88s all on the 32" tires. Now with the headers, muffler, tunes and 35"s it pulls our 11,300lb TT at 7/8 MPG on short trips on back roads with more stop and go traffic and 8/9 MPG on longer Interstate trips at 63/68 MPH. Bumping the speed up to 70/72 MPH drops it back down to 7.5-ish MPG.
Here is the tire size gear ratio calculator I use. 4Lo.com :: Tire Size Change, New Gear Ratio Calculator

 

Here is my thread on almost the same conversion and results.

https://www.ford-trucks.com/forums/1...n-options.html

 

If you have a sig, it didn't show, and since you haven't told us what engine you have (it matters greatly), we can't give an informed response.

Do you have a 5.4, 6.8, 7.3, or 6.0 engine?

Stewart

 

He has the good engine Stewart, you know the one that can survive with 4.88s.

 

Yup, the one that stops at every exit for gas.

 

Oh I figured he has a V10 based on your response, but still....well, you know what I'm trying to accomplish.

Besides, posting engine info is much akin to following SOP's at work, and since I like to brag that our Ex forum is really good at self-policing, if we don't hold people to the standard we've set, we are no longer self-policing.

Stewart

 

​​​​​​Thanks all for your info on tire size, lift and gearing as well as your experiences. My Ex is an 05 V10 with stock 3.73 and running 285/75R16s. I tried creating a signature line with my info but apparently didn't do it correctly. I stopped ato a local tire and wheel chain store today and I'm pretty sure I will go with the 275/65R20s on 20x9.5 -18mm wheels. I like the look of the narrower tire and it should work better for me in the deeper snow. Its just a matter of the gear choice now. Based on data from WE3ZS I should still be OK with 4.88s with my tire choice but since that size is actually 34.3 in the brand I'm looking at it may be best to stay with 4.56 which would give me a relative 4.20 ratio compared to the stock setup. I tow my 10.8K gross travel trailer less than 1000 miles per year. Other than that 90% of my driving is under 50 mph on back roads/10% highway at 65-70 mph.

im gonna go back and check the directions again in the welcome section to create a signature line with my truck info

 

the info I put in about my Ex is in my signature and I saved again. Do I need to click something to make it visible to everyone?

 

Hmmmm, 5 posts and 10 days registered so you're definitely ok there.

What happens when you preview your sig by clicking the "Preview" button after you've composed your sig?

Stewart

 

Stewart, when I hit preview it shows the info at the top in a preview box.

 

Thanks.

Need to pass this up the line.

Stewart