I drove a new 2015 f350 similar to my 08 (20K miles at the time) but with a much nicer ride. The owner told me one reason might be my 20 inch wheels vs. the '15 18 inch wheels with a larger, more flexible sidewall. I bought my truck used and it came with 20s. So now I need new tires and I'm considering downsizing the wheels. I have looked through the forum for advice and gotten some on another thread, but it is pretty confusing. Everyone else seems to be getting larger tires and it occurred to me the same thing could be achieved putting a larger tire on my 20 inch wheel. Is that true? If so, I wouldn't have to find new wheels or store/dispose of the 20s. Then there are TPMS issues, hub cover issues that would go away. But what about the speed-o? And the spare which is currently on an 18 inch rim? I found some 18 inch take-offs on Craig's List from a 2012 F250. Will these bolt right onto my 2008 F350? Any source for what years I can just swap wheels like that? Thanks much!

 

Wheels have nothing to do with it...........unless you install band aide type tires with no sidewall, then you'll get a very hard ride. Actually part of your suspension is the tires, if you go with a 285 or 295/75/20 tire and keep the psi around 65 psi it should ride pretty good......it is a truck though.

 

Thank you for the input. Yes, I realize it's a truck, and a fairly big one too, and I don't expect it to ride like a car. But I drove a later model of this truck similarly equipped and it was a smoother ride. So I was endeavoring to duplicate that feeling. One difference was the late model had 275/70R18 tires and mine has 275/65R20 so, smaller sidewall. Someone mentioned to me that the smaller sidewall could affect the ride so I was thinking about smaller wheels or larger tires.

Here is what I found. The dealer says putting anything on there other than what it says on the door pillar can damage the transmission and transfer case because when the vehicle is built Ford puts speed sensors that are dependent on those sizes. Therefore, if anything happens to my drivetrain the warranty will be void. I called a local tire dealer I trust and he concurred saying I could also experience issues with my brake calipers using the smaller wheel. So I give up. I will just put new tires on these wheels and hope for the best. I really do like this truck and I won't be disappointed. It is a truck, after all.

 

Ford dealer is giving you a line of horse****. The PCM can be programed for different sized tires and the speed sensors are basically the same and 18" wheels where available on '08's so they will clear the calipers as Ford didn't change the calipers when installing the 20's to a different one than the 18's used.

 

I agree with jetjockey 100%, My '16 F350 dually came with the little 17" tires/wheels which ....to me looked ridiculous. After I ordered my truck I started doing some research and bought the 20" tires and wheels which fit perfectly and ride very nice. Unfortunately most dealers don't know squat about these trucks so don't take it for gospel when they tell you something. If you look on craigslist there are quite a few 20" take offs for a very good price.

I also installed Bilstien shocks at the same time. When the truck came in I had the dealer re-program the PCM for the the 34" tires and install the DEF % info ....... the tires/wheels made a world of difference and really improved the looks.

 

Don't be fooled the smaller wheels will give you more sidewall and that WILL give you a better ride. Ford went with 20" because its more popular to run larger wheels.
I wish I could get 16" onto my 2006 but without grinding away 1/2" worth of my front calipers its not happening. The newer trucks I'm not real familiar with but sidewall is your friend.

I have 38/15.50/18 on my truck with Icon front coils along with Carli/Deaver rear leaf springs and it rides like a car.

 

I just gave up on this. I couldn't get consensus even in this thread, and in my area take offs are not that plentiful on CL. I had alerts for weeks and essentially I found one set of 18" wheel take-offs that were, in my opinion, overpriced. I have extended warranty on this truck and, ultimately, the people that are going to honor or deny claims have the most weight, even if they are full of crap. I just don't need the aggravation. I am convinced that a smaller wheel with the same diameter tire, by virtue of having a larger sidewall, will have more flex and a smoother ride. But is the improvement worth the effort and cost? No data available to confirm or quantify that. So I bought a set of Michelin defenders to replace my old tires and that closes this chapter for me. Thanks for all the inputs.

 

My steel 15" rims and 255/70/15 tires rode softer than my new alloy rims 17" with 255/60/17 tires. Side wall height and construction does make a difference. Same diameter tires and speedo is right on. My 2 cents.