I am strongly leaning toward a 2017 4x4 F350 CCSB 6.2L with 4.30 gears to tow a new 8500-9,000 lb max (loaded) bumper-pull travel trailer (we like going to the Rockies and Smokies!). The only thing I'm still not sure about is whether to go with 20" wheels. I like the looks of the 20" wheels because they seem more in proportion to the truck's size. The down side is that each tire will be about $50 more than comparable 18" tires, there is more mass (affecting economy and performance somewhat), and sometimes balancing larger tires can be an issue. Going with 20" wheels will negate some of the extra power to the ground I want with the 4.30 gears, but I'm thinking that I should still be much better off than with the 3.73 gears.

I'd welcome any insights, especially real-world experience. Thanks, y'all!

 

my insight is that most folks who ask this type of question will go with the larger rims reguardless of what others report....its human nature to let the gain out weight the risk.

from the 6 ford trucks in this class that I have owned, and 3 of them having upsized rims and tires added, my report would be as follows

a. I was never happy with the ride quality of the larger vs stock

b. I spent a lot of extra money beyond rims and tires on shocks, swaybars, over leaf kits to try to improve the ride

c. the larger tires did not have the highway speed of the smaller tires due to out of balance vibrtions

d. drive train problems like shudder manifest more with larger rims and tires

e. the larger rims and tires limted participation in car washes due to the guide track size.

f. I would always by a 5th rim and tire to use as a spare after an incident of trying to use a stock spare with larger rims and tires.

g. larger tires seemed bouncey, add more air and they hit like cinder blocks, hard to find the right PSI balance

h. definitely upgrade to dual horizontal steering stabilizers

yes, many have been there done this.

 

I tow a lot with 295/60/20"s and 3.73 gears. Mostly now my truck just stays hooked up to this three horse which is pushing 10g loaded(Two 5500lb axles). I'm averaging 9.5mpg on the computer. Sixth is absolutely useless and always locked out, even at upwards of 70mph. The truck gets around fine but revs and downshifts a lot. Mild exhaust work and tuning.

I don't have dual stabilizer, I don't have any weird drivetrain wobbles at 135,000+miles, I would never put my truck through an auto car wash regardless, and I find the ride super comfy and have no problems adjusting my air tire pressure. I do have a aftermarket rear stabilizer bar. And yes 20"s do look amazing on this truck. These are my favourite of the factory 20"s.

 

20s for looks, 18s for a better ride and more choices for tires. I like my oem 20s, but it definitely rides rougher than the 18s. I've found most high end tires are $100 more each.
Towing isn't affected either way. You need to have the correct tire pressure when towing.

 

I agree with speakerfritz about ride quality, but I have not experienced any of the other issue he is speaking about even with my current 37x13.50x20 Toyo RTs. I have purchased a larger spare tire "just in case".

It sounds to me like you are talking about factory options and not upsizing tires once you get the truck. If that is the case you will probably be fine with either option if you are towing a 9000 lb trailer. I just towed my 5th wheel through the Rockies. I had the combo scaled at 18,920 lbs before I loaded up. I figure it was up around 20k after we loaded up everything and it towed just fine with my setup.

 

The 20's look much better, there's plenty of choices of tires, none of the 20" tires have a problem with speed rating like a 19.5" comm'l tire ..... and I highly doubt you could tell too much difference in the ride. My truck rides better with the 20" Michelin Defenders than the stock 17.5" GY.

 

It's a proven fact that more sidewall will ride better. The less sidewall you have, the higher the air pressure needs to be to maintain load rating. Whether you have the ability to feel the difference is dependent on your personal abilities. 17.5 inch wheels are only available on DRW trucks and chassis's where towing capability trumps ride quality every time. Not exactly a fair comparison.

 

Good choice with the 6.2 and 4.30's, it will be a beast. I've been going through this as my new truck is coming w/17" steelies that I will take off asap. There will be no power difference between 18/20". It comes down to tire size that will have any affect on power. The taller the tire the more power loss. So from the factory: 275/70/18: 33.25" tall, 275/65/20:34.21" tall(AT3's). In factory form the 20" wheel choice will rob a little more power than the 18's. I feel the 20"s will work great with the 4.30's though.
I like the tire choices more in the 18" size. I would get the 295/70/18 in cooper maxx. Since I have found some 20" take offs, and I am set on the cooper maxx, I will be going with the 275/65/20.
I usually run all my tires near 80psi so I don't notice a ride quality difference.
Looking aftermarket, some of the 18" tires have a 4000lb load rating too, which beats most of the 20" tires by some margin.
I think you'd be happy with either one, so get the one you like the looks of better.

 

The biggest difference in ride quality will be psi. There is no reason to be running upwards of 80psi on your steer tires with a gas motor. I run 68 front and 78 rear and when I rotate I can immediately tell the difference if I don't change the psi.

Any load range e tire is going to handle any weight your truck can.

 

This has not been my experience. In fact the exact opposite I've found to be true. The more sidewall you have the more psi you need otherwise the tire will feel 'wobbly' under high weights. And weight ratings are given as far as I know at 80psi regardless of sidewall size.

So more sidewall might be more comfy but imo doesn't ride better, especially loaded up. The higher sidewall tire exhibits more 'tire roll' which to me is a worse ride.

This is my experience switching it up nearly daily between my '11 with 295/60/20's and my '03 with 265/75/16's.

 

Your sidewall height difference between those two tire sizes is less than 1". You must have a highly calibrated butt meter.

As far as max psi and weight ratings...that is determined by the manufacturer. My E rated Toyo RTs have a max weight rating of 3860 lbs at 65 psi.

Either way...I think we are talking about something that is subjective when it comes to ride quality. I agree with you on running lower psi when unloaded.

 

Yah at current tread levels a solid inch of difference in sidewall and 2.5-3" in width. Obviously different tires/trucks and no matter what rubber was wrapped on either one the '11 is going to be more comfy. Even though the '03 is in fantastic condition and highly maintained. I've been towing heavy with Ford 1tons for over 20 years now and the 20's for just the last year. The lower profile and way wider tire handle while towing way better than anything I've previously had on a 1ton. The ride loaded or empty isn't harsh and I feel much less tire roll than I do on my '03. No one would need that sensitive of a butt to feel the difference between the two tires.

Also I've been running e-rated tires just as long and I've never owned one that has its max rating at less than 80psi but I've never had many huge tires either. Those are some real nice looking treads you have I looked them up. I have a set of 37"s for my '95 that I could dust off in the barn and check though. Haven't run them for a couple of summers now as I just park the truck instead.

 

Get the wheels you want, with that weight and 4.30 gears, the trucks not going to have an issue.

 

It's true. Nitpicking 18's or 20's to death is pointless. Get the ones you want knowing that 20"s will have slightly more expensive rubber. Your choice in tire brand, style, and size along with how you set them up psi wise are going to have a lot more to do with ride/handling than the size of the hole in the middle.

 

Does the larger 20" rim fit under the truck? i believe my size is 265/75/20. (34.8) they are oem larait wheels