Newby to Superduty as well as diesel and just purchased a new/leftover 2023 F250 Crew with the 6.7L. It a long story but I was shopping for months for a 7.3L Godzilla to pull a 9k Lbs camper, when a long came a great deal on the diesel. The only issue with the purchase was settling on a truck with an awesome engine and package I needed, but had the crappy painted steel 17” rims & tires.

My question I know has been hashed through here in different forms but not to my specific situation I have. The 17” steels have to go, I’ve spent a life time working and nearing retirement and want not only a very functional truck, but I also want it to look good, or at least what I think looks good. I’ve never done any customization to any of my past trucks, so this maybe a first.

Here’s the questions: If I upsize to 18” or 20” OEM rims and tires, do I have to be concerned with my Ford warranty, I would hope not since they sell truck with those sizes, but? I’m leaning toward 20”, love the look on the F250.

I’m gearing stupid, the rear is 3.31, is the 20” going to have much of a change, more importantly any major negative impact in ratio?

I’ve read a little here on the speedo needing a tweak in the programming using FroScan. I’m tech savvy, but if I do this, is my factory warranty in jeopardy?

Lastly, reading here, I understand that the OEM rims in later models Super Duty’s are all interchangeable 17”, 18” & 20”. I have a friend with a set of 20” take offs the same year as mine, will they fit?



Thanks in advance for any help.

 

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Here’s the questions: If I upsize to 18” or 20” OEM rims and tires, do I have to be concerned with my Ford warranty,

• No

I’m gearing stupid, the rear is 3.73, is the 20” going to have much of a change, more importantly any major negative impact in ratio?

• See attached pic of the differences between 245/75-17 and 275/65-20
• The circumference is 8% bigger on the 20" OEM setup
• This will change your effective rear from 3.73:1 to 3.42:1
• Since the most popular rear end is the 3.31, you will have no problem, particularly with 1050 lbft of torque
• oops, have to correct myself ... you said 6.7l so I assumed the SO Diesel ... but the 3.73 is only avail with the 6.8l (Gas Flexfuel)
• since the 6.8 doesn't have the torque of the diesel, but instead has 445 lbft, you may actually be affected by the 8% change in rear
• Looking at your original post, you plan on towing a 9,000 lb trailer
• See attached pic (and link to) the 2023 Super Duty Towing Guide, this shows Crew Cab with the 6.8l gas and 3.73 rated to 14,100 lbs towing
• If we look at the chart more closely, it specifies that a 15% increase in rear end ratio (3.73 to 4.30) yields a 15% increase in rating (14,100 to 16,600)
• While not in the data set, I would be comfortable saying that an 8% decrease in rear end ratio (3.73 to 3.42) will yield well over 12,000 lbs
• Therefore I'd be comfortable towing 9,000 no problem

I’ve read a little here on the speedo needing a tweak in the programming using FroScan. I’m tech savvy, but if I do this, is my factory warranty in jeopardy?

• Yes you will need to make a change in ForScan, otherwise your speedo will read 8% low all the time
• No, no warranty issues

Lastly, reading here, I understand that the OEM rims in later models Super Duty’s are all interchangeable 17”, 18” & 20”. I have a friend with a set of 20” take offs the same year as mine, will they fit?

• Yes they will fit, buy your friend a beer

LINK to 2023 towing guide
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The SRW diesel only has 2 available factory gear ratios, 3.31 and 3.55. Both gear ratios are used with even the factory 20's. So that's a non issue. The speedo correction might depend on how far it's off, and if it's close enough to accurate for your liking. I imagine a jump from the 17" tire diameter to the 20" tire diameter might make a big enough speedo discrepancy to warrant a correction.

 

Wheels and tires are two different things.
You can get tires that fit 20" wheels, and have the same diameter as the stock 17" wheels. Same for 18".
If the rim backspacing is the same there wouldn't be any warranty concerns.
Most times the 'upgraded' wheel/tire combination have a larger diameter. You will need to adjust this to correct the transmission shift points and make it all work properly.

 

If you have the diesel higher gears are cool.

if you have the 6.8 then you want the lowest possible gears. 6.8 and 4:30s work well for my 9k 5th wheel. I would not want any higher gear or any larger tires to impact the gear ratio.

Does the srw come with 17inch steel wheels? I was under impression 17 was on the drw?????

 

I really appreciate the extremely detailed response! I screwed up on the rear ratio, I thought I knew it/remembered it, but it is a 3:31 electronic locking rear on a 6.7L Power Stroke "Reg Output" Diesel 4x4 Crew

 

Thanks for the reply, I screwed up on the rear ratio. Mine is 3:31 on a reg output 6.7L Power Stroke

 

My 2023 single rear wheel came with 17" painted steel wheels and is a diesel.

 

excellent ... then you should be totally fine, since the 1050lb ft is boatloads of torque

 

Thanks again wearenh for the help. Looking at the trailering capacity chart you provided, with the proper ratio selected, then would my towing capacity go from the 15,800 down approx to 14,536? "92% of 15,800lbs" ?

 

Your rated tow capacity does not change just because you change wheel/tire size. As mentioned previously, that 3.31 rear ratio is also used under the Super Duty's that came with 18" and 20" wheel/tire combinations.

 

I’m glad you had rear ratio mixed up vs motor.

 

Now that we have the engine and rear end correct, I think we can listen to what 4wd6.7L said:

I think the important part of the chart is where it says " ... based on trim series, option content, and payload." .... I have attached a chart of the 2024 tire sizes available ... the question is, which size did they use for the 15,800 rating? (which is based on a GCWR of 23,500) ... maybe someone here can point us to the answer ... each truck's door jamb label has GVWR and GAWR, which are specific for the trim level, wheels, and tires ... but where do you get the vehicle specific GCWR? ...




LINK to the Tire Size Comparison Calculator

 

Glad to know, I am going to pull the trigger on the 20" OEM Lariat take-offs with Michelin Tires. The rims are really nice and will definitely improve the look of my SD.

 

I towed the camper out of storage with it for the first ever tow on the new SD on Saturday and was beyond impressed with the power of the 6.7L & also the engine brake. I'm glad I ended up with the diesel & not the 7.3 gasser after that short 30 minute experience.